[alsa-devel] KMSAN: uninit-value in snd_midi_event_encode_byte
Hello,
syzbot found the following crash on:
HEAD commit: 2dca2cbde67a kmsan: fix build warnings with CONFIG_KMSAN=n git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=1660ef6a400000 kernel config: https://syzkaller.appspot.com/x/.config?x=820d6393634b55e3 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414)
Unfortunately, I don't have any reproducer for this crash yet.
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 0 PID: 1623 Comm: kworker/0:1H Not tainted 4.19.0-rc1+ #36 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xc9d/0x1660 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x17a6/0x67c0 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open fs/open.c:1076 [inline] __x64_sys_open+0xf2/0x130 fs/open.c:1076 do_syscall_64+0x15b/0x220 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
--- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot.
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: rawmidi: Initialize allocated buffers
syzbot reported the uninitialized value exposure in certain situations using virmidi loop. It's likely a very small race at writing and reading, and the influence is almost negligible. But it's safer to paper over this just by replacing the existing kvmalloc() with kvzalloc().
Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/rawmidi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c index 69517e18ef07..08d5662039e3 100644 --- a/sound/core/rawmidi.c +++ b/sound/core/rawmidi.c @@ -129,7 +129,7 @@ static int snd_rawmidi_runtime_create(struct snd_rawmidi_substream *substream) runtime->avail = 0; else runtime->avail = runtime->buffer_size; - runtime->buffer = kvmalloc(runtime->buffer_size, GFP_KERNEL); + runtime->buffer = kvzalloc(runtime->buffer_size, GFP_KERNEL); if (!runtime->buffer) { kfree(runtime); return -ENOMEM; @@ -655,7 +655,7 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime, if (params->avail_min < 1 || params->avail_min > params->buffer_size) return -EINVAL; if (params->buffer_size != runtime->buffer_size) { - newbuf = kvmalloc(params->buffer_size, GFP_KERNEL); + newbuf = kvzalloc(params->buffer_size, GFP_KERNEL); if (!newbuf) return -ENOMEM; spin_lock_irq(&runtime->lock);
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: rawmidi: Initialize allocated buffers
syzbot reported the uninitialized value exposure in certain situations using virmidi loop. It's likely a very small race at writing and reading, and the influence is almost negligible. But it's safer to paper over this just by replacing the existing kvmalloc() with kvzalloc().
Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de
sound/core/rawmidi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c index 69517e18ef07..08d5662039e3 100644 --- a/sound/core/rawmidi.c +++ b/sound/core/rawmidi.c @@ -129,7 +129,7 @@ static int snd_rawmidi_runtime_create(struct snd_rawmidi_substream *substream) runtime->avail = 0; else runtime->avail = runtime->buffer_size;
- runtime->buffer = kvmalloc(runtime->buffer_size, GFP_KERNEL);
- runtime->buffer = kvzalloc(runtime->buffer_size, GFP_KERNEL); if (!runtime->buffer) { kfree(runtime); return -ENOMEM;
@@ -655,7 +655,7 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime, if (params->avail_min < 1 || params->avail_min > params->buffer_size) return -EINVAL; if (params->buffer_size != runtime->buffer_size) {
newbuf = kvmalloc(params->buffer_size, GFP_KERNEL);
newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);-- 2.18.0
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
thanks,
Takashi
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: rawmidi: Initialize allocated buffers
syzbot reported the uninitialized value exposure in certain situations using virmidi loop. It's likely a very small race at writing and reading, and the influence is almost negligible. But it's safer to paper over this just by replacing the existing kvmalloc() with kvzalloc().
Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai tiwai@suse.de
sound/core/rawmidi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c index 69517e18ef07..08d5662039e3 100644 --- a/sound/core/rawmidi.c +++ b/sound/core/rawmidi.c @@ -129,7 +129,7 @@ static int snd_rawmidi_runtime_create(struct snd_rawmidi_substream *substream) runtime->avail = 0; else runtime->avail = runtime->buffer_size;
- runtime->buffer = kvmalloc(runtime->buffer_size, GFP_KERNEL);
- runtime->buffer = kvzalloc(runtime->buffer_size, GFP_KERNEL); if (!runtime->buffer) { kfree(runtime); return -ENOMEM;
@@ -655,7 +655,7 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime, if (params->avail_min < 1 || params->avail_min > params->buffer_size) return -EINVAL; if (params->buffer_size != runtime->buffer_size) {
newbuf = kvmalloc(params->buffer_size, GFP_KERNEL);
newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);-- 2.18.0
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that? I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
thanks,
Takashi
On Mon, Sep 3, 2018 at 3:37 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
syzbot has found a reproducer for the following crash on:
HEAD commit: 28f0ca98eadf kmsan: don't instrument do_syscall_64() and _.. git tree: https://github.com/google/kmsan.git/master console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 kernel config: https://syzkaller.appspot.com/x/.config?x=3431f03869413153 dashboard link: https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a compiler: clang version 8.0.0 (trunk 339414) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
================================================================== BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events_highpri snd_vmidi_output_work Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x14b/0x190 lib/dump_stack.c:113 kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 snd_midi_event_encode_byte+0x569/0xff0 sound/core/seq/seq_midi_event.c:195 snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was stored to memory at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 kthread+0x465/0x4a0 kernel/kthread.c:247 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
Uninit was created at: kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 kmalloc_node include/linux/slab.h:555 [inline] kvmalloc_node+0x19d/0x3e0 mm/util.c:423 kvmalloc include/linux/mm.h:577 [inline] snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 soundcore_open+0x9be/0xa60 sound/sound_core.c:597 chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 do_dentry_open+0xce6/0x1740 fs/open.c:771 vfs_open+0xaf/0xe0 fs/open.c:880 do_last fs/namei.c:3418 [inline] path_openat+0x1799/0x6870 fs/namei.c:3534 do_filp_open+0x259/0x610 fs/namei.c:3564 do_sys_open+0x630/0x940 fs/open.c:1063 __do_sys_open fs/open.c:1081 [inline] __se_sys_open+0xad/0xc0 fs/open.c:1076 __x64_sys_open+0x4a/0x70 fs/open.c:1076 do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7 ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that?
What exactly do you mean? Please elaborate.
I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
Just issue the command against "https://github.com/google/kmsan.git master" and attach the patch.
On Mon, 03 Sep 2018 15:41:36 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:37 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
On Mon, 03 Sep 2018 03:53:03 +0200, syzbot wrote:
> syzbot has found a reproducer for the following crash on:
> HEAD commit: 28f0ca98eadf kmsan: don't instrument > do_syscall_64() and _.. > git tree: https://github.com/google/kmsan.git/master > console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 > kernel config: > https://syzkaller.appspot.com/x/.config?x=3431f03869413153 > dashboard link: > https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a > compiler: clang version 8.0.0 (trunk 339414) > syz repro: > https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
> IMPORTANT: if you fix the bug, please add the following tag to the > commit: > Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
> ================================================================== > BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 > sound/core/seq/seq_midi_event.c:195 > CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 > Hardware name: Google Google Compute Engine/Google Compute Engine, > BIOS Google 01/01/2011 > Workqueue: events_highpri snd_vmidi_output_work > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x14b/0x190 lib/dump_stack.c:113 > kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 > __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 > snd_midi_event_encode_byte+0x569/0xff0 > sound/core/seq/seq_midi_event.c:195 > snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 > process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 > worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 > kthread+0x465/0x4a0 kernel/kthread.c:247 > ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
> Uninit was stored to memory at: > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] > kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] > kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 > __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 > __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] > snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 > snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 > process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 > worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 > kthread+0x465/0x4a0 kernel/kthread.c:247 > ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
> Uninit was created at: > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] > kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 > kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 > __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 > kmalloc_node include/linux/slab.h:555 [inline] > kvmalloc_node+0x19d/0x3e0 mm/util.c:423 > kvmalloc include/linux/mm.h:577 [inline] > snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] > open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 > rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 > snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 > soundcore_open+0x9be/0xa60 sound/sound_core.c:597 > chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 > do_dentry_open+0xce6/0x1740 fs/open.c:771 > vfs_open+0xaf/0xe0 fs/open.c:880 > do_last fs/namei.c:3418 [inline] > path_openat+0x1799/0x6870 fs/namei.c:3534 > do_filp_open+0x259/0x610 fs/namei.c:3564 > do_sys_open+0x630/0x940 fs/open.c:1063 > __do_sys_open fs/open.c:1081 [inline] > __se_sys_open+0xad/0xc0 fs/open.c:1076 > __x64_sys_open+0x4a/0x70 fs/open.c:1076 > do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 > entry_SYSCALL_64_after_hwframe+0x63/0xe7 > ==================================================================
This looks like some small race at virmidi reading and the buffer handling, which should be almost harmless by itself. Nevertheless, the fix should be easy, just replacing kvmalloc() with kvzalloc(), as below.
Let's check whether this works.
#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that?
What exactly do you mean? Please elaborate.
Well, it's not clear which action is required to let syzbot testing some patch. The description says:
"KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch)."
Here, "need to go to KMSAN tree" part doesn't explain what exactly to do. Remember that many kernel devs (including the man in the mirror) don't use github, at least, not dealing github PRs for kernel development itself, so it's a pretty unfamiliar process.
I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
Just issue the command against "https://github.com/google/kmsan.git master" and attach the patch.
But it's basically a fix for the upstream tree, not about KMSAN itself. A PR to that tree doesn't sound right to me...
thanks,
Takashi
On Mon, Sep 3, 2018 at 4:04 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:41:36 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:37 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote:
> On Mon, 03 Sep 2018 03:53:03 +0200, > syzbot wrote:
>> syzbot has found a reproducer for the following crash on:
>> HEAD commit: 28f0ca98eadf kmsan: don't instrument >> do_syscall_64() and _.. >> git tree: https://github.com/google/kmsan.git/master >> console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 >> kernel config: >> https://syzkaller.appspot.com/x/.config?x=3431f03869413153 >> dashboard link: >> https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a >> compiler: clang version 8.0.0 (trunk 339414) >> syz repro: >> https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000
>> IMPORTANT: if you fix the bug, please add the following tag to the >> commit: >> Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
>> ================================================================== >> BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 >> sound/core/seq/seq_midi_event.c:195 >> CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 >> Hardware name: Google Google Compute Engine/Google Compute Engine, >> BIOS Google 01/01/2011 >> Workqueue: events_highpri snd_vmidi_output_work >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x14b/0x190 lib/dump_stack.c:113 >> kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 >> __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 >> snd_midi_event_encode_byte+0x569/0xff0 >> sound/core/seq/seq_midi_event.c:195 >> snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 >> kthread+0x465/0x4a0 kernel/kthread.c:247 >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
>> Uninit was stored to memory at: >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] >> kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] >> kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 >> __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 >> __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] >> snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 >> snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 >> kthread+0x465/0x4a0 kernel/kthread.c:247 >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416
>> Uninit was created at: >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] >> kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 >> kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 >> __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 >> kmalloc_node include/linux/slab.h:555 [inline] >> kvmalloc_node+0x19d/0x3e0 mm/util.c:423 >> kvmalloc include/linux/mm.h:577 [inline] >> snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] >> open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 >> rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 >> snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 >> soundcore_open+0x9be/0xa60 sound/sound_core.c:597 >> chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 >> do_dentry_open+0xce6/0x1740 fs/open.c:771 >> vfs_open+0xaf/0xe0 fs/open.c:880 >> do_last fs/namei.c:3418 [inline] >> path_openat+0x1799/0x6870 fs/namei.c:3534 >> do_filp_open+0x259/0x610 fs/namei.c:3564 >> do_sys_open+0x630/0x940 fs/open.c:1063 >> __do_sys_open fs/open.c:1081 [inline] >> __se_sys_open+0xad/0xc0 fs/open.c:1076 >> __x64_sys_open+0x4a/0x70 fs/open.c:1076 >> do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 >> entry_SYSCALL_64_after_hwframe+0x63/0xe7 >> ==================================================================
> This looks like some small race at virmidi reading and the buffer > handling, which should be almost harmless by itself. > Nevertheless, the fix should be easy, just replacing kvmalloc() with > kvzalloc(), as below.
> Let's check whether this works.
> #syz test: > git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git > topic/rawmidi-fixes
KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree because KMSAN tool is not upstreamed yet. See https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that?
What exactly do you mean? Please elaborate.
Well, it's not clear which action is required to let syzbot testing some patch. The description says:
"KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch)."
Here, "need to go to KMSAN tree" part doesn't explain what exactly to do. Remember that many kernel devs (including the man in the mirror) don't use github, at least, not dealing github PRs for kernel development itself, so it's a pretty unfamiliar process.
It's not patches that need to go into that tree (i.e. no PRs). It's patch testing requests.
Tried to clarify doc:
https://github.com/google/syzkaller/commit/bfe906cbb9c73c326f24327e1a89bc0cd...
Does this look better?
I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
Just issue the command against "https://github.com/google/kmsan.git master" and attach the patch.
But it's basically a fix for the upstream tree, not about KMSAN itself. A PR to that tree doesn't sound right to me...
You don't need to send a PR. You attach a patch (or inline in email) and request to apply and test it in KMSAN tree.
On Mon, 03 Sep 2018 16:19:23 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 4:04 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:41:36 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:37 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:22:42 +0200, syzbot wrote: > > > On Mon, 03 Sep 2018 03:53:03 +0200, > > syzbot wrote: > > >> syzbot has found a reproducer for the following crash on: > > >> HEAD commit: 28f0ca98eadf kmsan: don't instrument > >> do_syscall_64() and _.. > >> git tree: https://github.com/google/kmsan.git/master > >> console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 > >> kernel config: > >> https://syzkaller.appspot.com/x/.config?x=3431f03869413153 > >> dashboard link: > >> https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a > >> compiler: clang version 8.0.0 (trunk 339414) > >> syz repro: > >> https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 > >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000 > > >> IMPORTANT: if you fix the bug, please add the following tag to the > >> commit: > >> Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com > > >> ================================================================== > >> BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 > >> sound/core/seq/seq_midi_event.c:195 > >> CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 > >> Hardware name: Google Google Compute Engine/Google Compute Engine, > >> BIOS Google 01/01/2011 > >> Workqueue: events_highpri snd_vmidi_output_work > >> Call Trace: > >> __dump_stack lib/dump_stack.c:77 [inline] > >> dump_stack+0x14b/0x190 lib/dump_stack.c:113 > >> kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 > >> __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 > >> snd_midi_event_encode_byte+0x569/0xff0 > >> sound/core/seq/seq_midi_event.c:195 > >> snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 > >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 > >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 > >> kthread+0x465/0x4a0 kernel/kthread.c:247 > >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416 > > >> Uninit was stored to memory at: > >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] > >> kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] > >> kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 > >> __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 > >> __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] > >> snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 > >> snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 > >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 > >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 > >> kthread+0x465/0x4a0 kernel/kthread.c:247 > >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416 > > >> Uninit was created at: > >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] > >> kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 > >> kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 > >> __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 > >> kmalloc_node include/linux/slab.h:555 [inline] > >> kvmalloc_node+0x19d/0x3e0 mm/util.c:423 > >> kvmalloc include/linux/mm.h:577 [inline] > >> snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] > >> open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 > >> rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 > >> snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 > >> soundcore_open+0x9be/0xa60 sound/sound_core.c:597 > >> chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 > >> do_dentry_open+0xce6/0x1740 fs/open.c:771 > >> vfs_open+0xaf/0xe0 fs/open.c:880 > >> do_last fs/namei.c:3418 [inline] > >> path_openat+0x1799/0x6870 fs/namei.c:3534 > >> do_filp_open+0x259/0x610 fs/namei.c:3564 > >> do_sys_open+0x630/0x940 fs/open.c:1063 > >> __do_sys_open fs/open.c:1081 [inline] > >> __se_sys_open+0xad/0xc0 fs/open.c:1076 > >> __x64_sys_open+0x4a/0x70 fs/open.c:1076 > >> do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 > >> entry_SYSCALL_64_after_hwframe+0x63/0xe7 > >> ================================================================== > > > This looks like some small race at virmidi reading and the buffer > > handling, which should be almost harmless by itself. > > Nevertheless, the fix should be easy, just replacing kvmalloc() with > > kvzalloc(), as below. > > > Let's check whether this works. > > > #syz test: > > git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git > > topic/rawmidi-fixes > > KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree > because KMSAN tool is not upstreamed yet. > See > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs > for details.
So how is the procedure to test a patch for bugs spotted by KMSAN?
In this case, the fix is trivial, so I can put it to my tree for the next pull request. Of course, it'd be better if it can be confirmed to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that?
What exactly do you mean? Please elaborate.
Well, it's not clear which action is required to let syzbot testing some patch. The description says:
"KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch)."
Here, "need to go to KMSAN tree" part doesn't explain what exactly to do. Remember that many kernel devs (including the man in the mirror) don't use github, at least, not dealing github PRs for kernel development itself, so it's a pretty unfamiliar process.
It's not patches that need to go into that tree (i.e. no PRs). It's patch testing requests.
Tried to clarify doc:
https://github.com/google/syzkaller/commit/bfe906cbb9c73c326f24327e1a89bc0cd...
Does this look better?
Erm, sorry, still unclear to me. I'd need to explicitl attch/inline the patch for testing *to where*? Attach the test patch to the e-mail replying to the bug?
Also, now you've put an example referring to https://github.com/google/kmsan.git master. What does it mean? I should have put that line in my reply?
I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
Just issue the command against "https://github.com/google/kmsan.git master" and attach the patch.
But it's basically a fix for the upstream tree, not about KMSAN itself. A PR to that tree doesn't sound right to me...
You don't need to send a PR. You attach a patch (or inline in email) and request to apply and test it in KMSAN tree.
Then I must have understood "just issue the command against..." Does it mean the "syz test: https//github.com/google/kmsan.git master"?
I need to learn the basic for understanding the black magic...
thanks,
Takashi
On Mon, Sep 3, 2018 at 4:30 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 16:19:23 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 4:04 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:41:36 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:37 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 15:33:12 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 3:29 PM, Takashi Iwai tiwai@suse.de wrote: > On Mon, 03 Sep 2018 15:22:42 +0200, > syzbot wrote: >> >> > On Mon, 03 Sep 2018 03:53:03 +0200, >> > syzbot wrote: >> >> >> syzbot has found a reproducer for the following crash on: >> >> >> HEAD commit: 28f0ca98eadf kmsan: don't instrument >> >> do_syscall_64() and _.. >> >> git tree: https://github.com/google/kmsan.git/master >> >> console output: https://syzkaller.appspot.com/x/log.txt?x=10556c92400000 >> >> kernel config: >> >> https://syzkaller.appspot.com/x/.config?x=3431f03869413153 >> >> dashboard link: >> >> https://syzkaller.appspot.com/bug?extid=194dffdb8b22fc5d207a >> >> compiler: clang version 8.0.0 (trunk 339414) >> >> syz repro: >> >> https://syzkaller.appspot.com/x/repro.syz?x=123a520a400000 >> >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16068dc1400000 >> >> >> IMPORTANT: if you fix the bug, please add the following tag to the >> >> commit: >> >> Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com >> >> >> ================================================================== >> >> BUG: KMSAN: uninit-value in snd_midi_event_encode_byte+0x569/0xff0 >> >> sound/core/seq/seq_midi_event.c:195 >> >> CPU: 1 PID: 1659 Comm: kworker/1:1H Not tainted 4.19.0-rc1+ #40 >> >> Hardware name: Google Google Compute Engine/Google Compute Engine, >> >> BIOS Google 01/01/2011 >> >> Workqueue: events_highpri snd_vmidi_output_work >> >> Call Trace: >> >> __dump_stack lib/dump_stack.c:77 [inline] >> >> dump_stack+0x14b/0x190 lib/dump_stack.c:113 >> >> kmsan_report+0x183/0x2b0 mm/kmsan/kmsan.c:956 >> >> __msan_warning+0x70/0xc0 mm/kmsan/kmsan_instr.c:645 >> >> snd_midi_event_encode_byte+0x569/0xff0 >> >> sound/core/seq/seq_midi_event.c:195 >> >> snd_vmidi_output_work+0x34e/0x5b0 sound/core/seq/seq_virmidi.c:161 >> >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 >> >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 >> >> kthread+0x465/0x4a0 kernel/kthread.c:247 >> >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416 >> >> >> Uninit was stored to memory at: >> >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] >> >> kmsan_save_stack mm/kmsan/kmsan.c:271 [inline] >> >> kmsan_internal_chain_origin+0x128/0x210 mm/kmsan/kmsan.c:573 >> >> __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:482 >> >> __snd_rawmidi_transmit_peek sound/core/rawmidi.c:1103 [inline] >> >> snd_rawmidi_transmit+0xa75/0xbf0 sound/core/rawmidi.c:1228 >> >> snd_vmidi_output_work+0x2ac/0x5b0 sound/core/seq/seq_virmidi.c:159 >> >> process_one_work+0x1605/0x1f40 kernel/workqueue.c:2153 >> >> worker_thread+0x11a2/0x2590 kernel/workqueue.c:2296 >> >> kthread+0x465/0x4a0 kernel/kthread.c:247 >> >> ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:416 >> >> >> Uninit was created at: >> >> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:256 [inline] >> >> kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:181 >> >> kmsan_kmalloc+0x98/0x100 mm/kmsan/kmsan_hooks.c:91 >> >> __kmalloc_node+0x7bf/0x11c0 mm/slub.c:3828 >> >> kmalloc_node include/linux/slab.h:555 [inline] >> >> kvmalloc_node+0x19d/0x3e0 mm/util.c:423 >> >> kvmalloc include/linux/mm.h:577 [inline] >> >> snd_rawmidi_runtime_create sound/core/rawmidi.c:132 [inline] >> >> open_substream+0x3c8/0xaa0 sound/core/rawmidi.c:276 >> >> rawmidi_open_priv+0x347/0x1000 sound/core/rawmidi.c:327 >> >> snd_rawmidi_open+0x7d4/0x1120 sound/core/rawmidi.c:424 >> >> soundcore_open+0x9be/0xa60 sound/sound_core.c:597 >> >> chrdev_open+0xc26/0xdb0 fs/char_dev.c:417 >> >> do_dentry_open+0xce6/0x1740 fs/open.c:771 >> >> vfs_open+0xaf/0xe0 fs/open.c:880 >> >> do_last fs/namei.c:3418 [inline] >> >> path_openat+0x1799/0x6870 fs/namei.c:3534 >> >> do_filp_open+0x259/0x610 fs/namei.c:3564 >> >> do_sys_open+0x630/0x940 fs/open.c:1063 >> >> __do_sys_open fs/open.c:1081 [inline] >> >> __se_sys_open+0xad/0xc0 fs/open.c:1076 >> >> __x64_sys_open+0x4a/0x70 fs/open.c:1076 >> >> do_syscall_64+0xb8/0x100 arch/x86/entry/common.c:291 >> >> entry_SYSCALL_64_after_hwframe+0x63/0xe7 >> >> ================================================================== >> >> > This looks like some small race at virmidi reading and the buffer >> > handling, which should be almost harmless by itself. >> > Nevertheless, the fix should be easy, just replacing kvmalloc() with >> > kvzalloc(), as below. >> >> > Let's check whether this works. >> >> > #syz test: >> > git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git >> > topic/rawmidi-fixes >> >> KMSAN bugs can only be tested on https://github.com/google/kmsan.git tree >> because KMSAN tool is not upstreamed yet. >> See >> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs >> for details. > > So how is the procedure to test a patch for bugs spotted by KMSAN? > > In this case, the fix is trivial, so I can put it to my tree for the > next pull request. Of course, it'd be better if it can be confirmed > to work beforehand...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs
Which means you need to attach a patch because it's not in that tree.
OK, it would have been helpful if the description there was more clear :)
And no automated way for that?
What exactly do you mean? Please elaborate.
Well, it's not clear which action is required to let syzbot testing some patch. The description says:
"KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch)."
Here, "need to go to KMSAN tree" part doesn't explain what exactly to do. Remember that many kernel devs (including the man in the mirror) don't use github, at least, not dealing github PRs for kernel development itself, so it's a pretty unfamiliar process.
It's not patches that need to go into that tree (i.e. no PRs). It's patch testing requests.
Tried to clarify doc:
https://github.com/google/syzkaller/commit/bfe906cbb9c73c326f24327e1a89bc0cd...
Does this look better?
Erm, sorry, still unclear to me. I'd need to explicitl attch/inline the patch for testing *to where*? Attach the test patch to the e-mail replying to the bug?
Also, now you've put an example referring to https://github.com/google/kmsan.git master. What does it mean? I should have put that line in my reply?
I mean, I already attached patch in the previous reply (together with syz-magic command to point the git branch URL). Do I need anything else?
Just issue the command against "https://github.com/google/kmsan.git master" and attach the patch.
But it's basically a fix for the upstream tree, not about KMSAN itself. A PR to that tree doesn't sound right to me...
You don't need to send a PR. You attach a patch (or inline in email) and request to apply and test it in KMSAN tree.
Then I must have understood "just issue the command against..." Does it mean the "syz test: https//github.com/google/kmsan.git master"?
I need to learn the basic for understanding the black magic...
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
On Mon, 03 Sep 2018 16:54:23 +0200, Dmitry Vyukov wrote:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
OK, so far, so good, it's what I knew and have done a few times.
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
Sorry, the part "issue test request against https..." still isn't clear.
Do you mean to open an issue entry on github, and attach the patch there?
Takashi
On Mon, Sep 3, 2018 at 5:00 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 16:54:23 +0200, Dmitry Vyukov wrote:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
OK, so far, so good, it's what I knew and have done a few times.
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
Sorry, the part "issue test request against https..." still isn't clear.
Do you mean to open an issue entry on github, and attach the patch there?
By "issue test request" I mean sending email with "syz test" command. So overall you send "syz test https//github.com/google/kmsan.git master" and attach the patch. The workflow is all the same, and no github involved. It's just that you can't ask to test it against git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git because it does not have KMSAN tool and so no KMSAN bugs will be detected there.
Since I did all of this, it's hard for me to write clear docs for others. Sorry. If you can suggest some improved wording, it would be great.
On Mon, 03 Sep 2018 17:06:05 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 5:00 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 16:54:23 +0200, Dmitry Vyukov wrote:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
OK, so far, so good, it's what I knew and have done a few times.
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
Sorry, the part "issue test request against https..." still isn't clear.
Do you mean to open an issue entry on github, and attach the patch there?
By "issue test request" I mean sending email with "syz test" command. So overall you send "syz test https//github.com/google/kmsan.git master" and attach the patch. The workflow is all the same, and no github involved. It's just that you can't ask to test it against git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git because it does not have KMSAN tool and so no KMSAN bugs will be detected there.
Thanks, this finally made me understanding the whole picture!
Since I did all of this, it's hard for me to write clear docs for others. Sorry. If you can suggest some improved wording, it would be great.
Well, how about like below?
KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch). A standard way for triggering the test with KMSAN tree is to send an email to syzbot+HASH address containing the following line:
#syz test: https://github.com/google/kmsan.git master
and attach/inline your test patch in the same mail.
Takashi
On Mon, Sep 3, 2018 at 5:18 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 17:06:05 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 5:00 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 16:54:23 +0200, Dmitry Vyukov wrote:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
OK, so far, so good, it's what I knew and have done a few times.
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
Sorry, the part "issue test request against https..." still isn't clear.
Do you mean to open an issue entry on github, and attach the patch there?
By "issue test request" I mean sending email with "syz test" command. So overall you send "syz test https//github.com/google/kmsan.git master" and attach the patch. The workflow is all the same, and no github involved. It's just that you can't ask to test it against git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git because it does not have KMSAN tool and so no KMSAN bugs will be detected there.
Thanks, this finally made me understanding the whole picture!
Since I did all of this, it's hard for me to write clear docs for others. Sorry. If you can suggest some improved wording, it would be great.
Well, how about like below?
KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch). A standard way for triggering the test with KMSAN tree is to send an email to syzbot+HASH address containing the following line:
#syz test: https://github.com/google/kmsan.git master
and attach/inline your test patch in the same mail.
Done: https://github.com/google/syzkaller/commit/3ea6c028b154d2faea45142bfb15b02f3...
Thanks
On Mon, 03 Sep 2018 19:25:39 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 5:18 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 17:06:05 +0200, Dmitry Vyukov wrote:
On Mon, Sep 3, 2018 at 5:00 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 03 Sep 2018 16:54:23 +0200, Dmitry Vyukov wrote:
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#kmsan-bugs is meant to be a complement to the previous generic descriptions of patch testing process, which is: https://github.com/google/syzkaller/blob/master/docs/syzbot.md#testing-patch...
So, you always reply to the syzbot+HASH email address so that syzbot understands which bug we are talking about. Then you do either (omitting # so that syzbot won't consider that as actual test requests):
syz test: git://repo/address.git branch
or:
syz test: git://repo/address.git commit-hash
And then you can either attach a patch that needs to be applied on top, or not attach it (if it's already in the tree, or you just want to get another crash report).
OK, so far, so good, it's what I knew and have done a few times.
For KMSAN you need to issue test request against "https//github.com/google/kmsan.git master" (that's the only tree that has KMSAN tool in it) and you need to attach/inline the patch (because your patch is obviously not there yet).
Does this make things more clear?
Sorry, the part "issue test request against https..." still isn't clear.
Do you mean to open an issue entry on github, and attach the patch there?
By "issue test request" I mean sending email with "syz test" command. So overall you send "syz test https//github.com/google/kmsan.git master" and attach the patch. The workflow is all the same, and no github involved. It's just that you can't ask to test it against git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git because it does not have KMSAN tool and so no KMSAN bugs will be detected there.
Thanks, this finally made me understanding the whole picture!
Since I did all of this, it's hard for me to write clear docs for others. Sorry. If you can suggest some improved wording, it would be great.
Well, how about like below?
KMSAN is not upstream yet, though, we want to upstream it later. For now, it lives in github.com/google/kmsan and is based on a reasonably fresh upstream tree. As the result, any patch testing requests for KMSAN bugs need to go to KMSAN tree (https://github.com/google/kmsan.git repo, master branch). A standard way for triggering the test with KMSAN tree is to send an email to syzbot+HASH address containing the following line:
#syz test: https://github.com/google/kmsan.git master
and attach/inline your test patch in the same mail.
Done: https://github.com/google/syzkaller/commit/3ea6c028b154d2faea45142bfb15b02f3...
Thanks!
And about the bug in the subject: as syzbot returned a positive feedback for my test patch, I queued it to for-linus branch now.
Takashi
participants (3)
-
Dmitry Vyukov -
syzbot -
Takashi Iwai