[alsa-devel] usb/midi: use-after-free in snd_rawmidi_dev_seq_free
Hi!
While working on adding USB fuzzing support to syzkaller, I got the following crash.
On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
My .config is attached. I don't have a reproducer for this bug.
================================================================== BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
Allocated by task 567: save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551 kmem_cache_alloc_trace+0x66/0x170 mm/slub.c:2739 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:666 [inline] snd_rawmidi_new+0x111/0x500 sound/core/rawmidi.c:1535 snd_usbmidi_create_rawmidi sound/usb/midi.c:2221 [inline] __snd_usbmidi_create+0x5cb/0x2700 sound/usb/midi.c:2450 snd_usbmidi_create sound/usb/midi.h:53 [inline] create_any_midi_quirk+0x54/0x70 sound/usb/quirks.c:103 snd_usb_create_quirk+0x92/0x100 sound/usb/quirks.c:561 usb_audio_probe+0xf98/0x2aa0 sound/usb/card.c:598 usb_probe_interface+0x351/0x8d0 drivers/usb/core/driver.c:361 really_probe drivers/base/dd.c:385 [inline] driver_probe_device+0x610/0xa00 drivers/base/dd.c:529 __device_attach_driver+0x230/0x290 drivers/base/dd.c:625 bus_for_each_drv+0x15e/0x210 drivers/base/bus.c:463 __device_attach+0x269/0x3c0 drivers/base/dd.c:682 device_initial_probe+0x1f/0x30 drivers/base/dd.c:729 bus_probe_device+0x1da/0x280 drivers/base/bus.c:523 device_add+0xcf9/0x1640 drivers/base/core.c:1703 usb_set_configuration+0x1064/0x1890 drivers/usb/core/message.c:1932 generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174 usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266 really_probe drivers/base/dd.c:385 [inline] driver_probe_device+0x610/0xa00 drivers/base/dd.c:529 __device_attach_driver+0x230/0x290 drivers/base/dd.c:625 bus_for_each_drv+0x15e/0x210 drivers/base/bus.c:463 __device_attach+0x269/0x3c0 drivers/base/dd.c:682 device_initial_probe+0x1f/0x30 drivers/base/dd.c:729 bus_probe_device+0x1da/0x280 drivers/base/bus.c:523 device_add+0xcf9/0x1640 drivers/base/core.c:1703 usb_new_device+0x91d/0x17a0 drivers/usb/core/hub.c:2457 hub_port_connect drivers/usb/core/hub.c:4890 [inline] hub_port_connect_change drivers/usb/core/hub.c:4996 [inline] port_event drivers/usb/core/hub.c:5102 [inline] hub_event+0x261c/0x3960 drivers/usb/core/hub.c:5186 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
Freed by task 1454: save_stack_trace+0x1b/0x20 arch/x86/kernel/stacktrace.c:59 save_stack+0x43/0xd0 mm/kasan/kasan.c:447 set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0x72/0xc0 mm/kasan/kasan.c:524 slab_free_hook mm/slub.c:1357 [inline] slab_free_freelist_hook mm/slub.c:1379 [inline] slab_free mm/slub.c:2955 [inline] kfree+0x96/0x1a0 mm/slub.c:3883 release_rawmidi_device+0x1e/0x30 sound/core/rawmidi.c:1502 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 snd_rawmidi_free.part.15+0x14b/0x190 sound/core/rawmidi.c:1603 snd_rawmidi_free sound/core/rawmidi.c:1589 [inline] snd_rawmidi_dev_free+0x43/0x60 sound/core/rawmidi.c:1610 __snd_device_free+0x1e5/0x380 sound/core/device.c:91 snd_device_free_all+0x8f/0xe0 sound/core/device.c:244 snd_card_do_free sound/core/init.c:463 [inline] release_card_device+0x26/0x150 sound/core/init.c:181 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 snd_card_free_when_closed+0x34/0x50 sound/core/init.c:491 usb_audio_disconnect+0x5fb/0x860 sound/usb/card.c:684 usb_unbind_interface+0x216/0xa90 drivers/usb/core/driver.c:423 __device_release_driver drivers/base/dd.c:833 [inline] device_release_driver_internal+0x4da/0x5a0 drivers/base/dd.c:863 device_release_driver+0x1e/0x30 drivers/base/dd.c:888 bus_remove_device+0x2da/0x490 drivers/base/bus.c:565 device_del+0x5b1/0xaa0 drivers/base/core.c:1853 usb_disable_device+0x1e9/0x680 drivers/usb/core/message.c:1170 usb_disconnect+0x2ca/0x830 drivers/usb/core/hub.c:2124 hub_port_connect drivers/usb/core/hub.c:4741 [inline] hub_port_connect_change drivers/usb/core/hub.c:4996 [inline] port_event drivers/usb/core/hub.c:5102 [inline] hub_event+0x14d8/0x3960 drivers/usb/core/hub.c:5186 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
The buggy address belongs to the object at ffff88006c611980 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 1040 bytes inside of 2048-byte region [ffff88006c611980, ffff88006c612180) The buggy address belongs to the page: page:ffffea0001b18400 count:1 mapcount:0 mapping: (null) index:0xffff88006c617700 compound_mapcount: 0 flags: 0x500000000008100(slab|head) raw: 0500000000008100 0000000000000000 ffff88006c617700 00000001800f0007 raw: ffffea0001b10400 0000000300000003 ffff88003e803040 0000000000000000 page dumped because: kasan: bad access detected
Memory state around the buggy address: ffff88006c611c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88006c611d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88006c611d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff88006c611e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88006c611e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
On Tue, 05 Sep 2017 13:12:14 +0200, Andrey Konovalov wrote:
Hi!
While working on adding USB fuzzing support to syzkaller, I got the following crash.
On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
My .config is attached. I don't have a reproducer for this bug.
================================================================== BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
So this looks like a pending work triggering the issue when performed during the card free. What about the patch below as a quick band-aid fix?
thanks,
Takashi
--- diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void) flush_work(&autoload_work); } EXPORT_SYMBOL(snd_seq_device_load_drivers); +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work) #else #define queue_autoload_drivers() /* NOP */ +#define cancel_autoload_drivers() /* NOP */ #endif
/* @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device) { struct snd_seq_device *dev = device->device_data;
+ cancel_autoload_drivers(); put_device(&dev->dev); return 0; }
On Tue, Sep 5, 2017 at 6:08 PM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 05 Sep 2017 13:12:14 +0200, Andrey Konovalov wrote:
Hi!
While working on adding USB fuzzing support to syzkaller, I got the following crash.
On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
My .config is attached. I don't have a reproducer for this bug.
================================================================== BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
So this looks like a pending work triggering the issue when performed during the card free. What about the patch below as a quick band-aid fix?
thanks,
Takashi
Hi Takashi,
I've been running syzkaller with your patch for a few days and didn't see any more of those reports.
Tested-by: Andrey Konovalov andreyknvl@google.com
Thanks!
diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void) flush_work(&autoload_work); } EXPORT_SYMBOL(snd_seq_device_load_drivers); +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work) #else #define queue_autoload_drivers() /* NOP */ +#define cancel_autoload_drivers() /* NOP */ #endif
/* @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device) { struct snd_seq_device *dev = device->device_data;
cancel_autoload_drivers(); put_device(&dev->dev); return 0;}
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On Mon, 11 Sep 2017 13:17:39 +0200, Andrey Konovalov wrote:
On Tue, Sep 5, 2017 at 6:08 PM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 05 Sep 2017 13:12:14 +0200, Andrey Konovalov wrote:
Hi!
While working on adding USB fuzzing support to syzkaller, I got the following crash.
On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
My .config is attached. I don't have a reproducer for this bug.
================================================================== BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
So this looks like a pending work triggering the issue when performed during the card free. What about the patch below as a quick band-aid fix?
thanks,
Takashi
Hi Takashi,
I've been running syzkaller with your patch for a few days and didn't see any more of those reports.
Tested-by: Andrey Konovalov andreyknvl@google.com
Thanks, I merged the fix now. FWIW, below is the official patch I merged.
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: seq: Cancel pending autoload work at unbinding device
ALSA sequencer core has a mechanism to load the enumerated devices automatically, and it's performed in an off-load work. This seems causing some race when a sequencer is removed while the pending autoload work is running. As syzkaller spotted, it may lead to some use-after-free: BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
The fix is simply to assure canceling the autoload work at removing the device.
Reported-by: Andrey Konovalov andreyknvl@google.com Tested-by: Andrey Konovalov andreyknvl@google.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/seq_device.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c index c4acf17e9f5e..e40a2cba5002 100644 --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void) flush_work(&autoload_work); } EXPORT_SYMBOL(snd_seq_device_load_drivers); +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work) #else #define queue_autoload_drivers() /* NOP */ +#define cancel_autoload_drivers() /* NOP */ #endif
/* @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device) { struct snd_seq_device *dev = device->device_data;
+ cancel_autoload_drivers(); put_device(&dev->dev); return 0; }
On Tue, Sep 12, 2017 at 12:46 PM, Takashi Iwai tiwai@suse.de wrote:
On Mon, 11 Sep 2017 13:17:39 +0200, Andrey Konovalov wrote:
On Tue, Sep 5, 2017 at 6:08 PM, Takashi Iwai tiwai@suse.de wrote:
On Tue, 05 Sep 2017 13:12:14 +0200, Andrey Konovalov wrote:
Hi!
While working on adding USB fuzzing support to syzkaller, I got the following crash.
On commit 81a84ad3cb5711cec79f4dd53a4ce026b092c432 (4.13+).
My .config is attached. I don't have a reproducer for this bug.
================================================================== BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
So this looks like a pending work triggering the issue when performed during the card free. What about the patch below as a quick band-aid fix?
thanks,
Takashi
Hi Takashi,
I've been running syzkaller with your patch for a few days and didn't see any more of those reports.
Tested-by: Andrey Konovalov andreyknvl@google.com
Thanks, I merged the fix now. FWIW, below is the official patch I merged.
Great, thanks!
Takashi
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: seq: Cancel pending autoload work at unbinding device
ALSA sequencer core has a mechanism to load the enumerated devices automatically, and it's performed in an off-load work. This seems causing some race when a sequencer is removed while the pending autoload work is running. As syzkaller spotted, it may lead to some use-after-free: BUG: KASAN: use-after-free in snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 Write of size 8 at addr ffff88006c611d90 by task kworker/2:1/567
CPU: 2 PID: 567 Comm: kworker/2:1 Not tainted 4.13.0+ #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Workqueue: events autoload_drivers Call Trace: __dump_stack lib/dump_stack.c:16 [inline] dump_stack+0x192/0x22c lib/dump_stack.c:52 print_address_description+0x78/0x280 mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report+0x230/0x340 mm/kasan/report.c:409 __asan_report_store8_noabort+0x1c/0x20 mm/kasan/report.c:435 snd_rawmidi_dev_seq_free+0x69/0x70 sound/core/rawmidi.c:1617 snd_seq_dev_release+0x4f/0x70 sound/core/seq_device.c:192 device_release+0x13f/0x210 drivers/base/core.c:814 kobject_cleanup lib/kobject.c:648 [inline] kobject_release lib/kobject.c:677 [inline] kref_put include/linux/kref.h:70 [inline] kobject_put+0x145/0x240 lib/kobject.c:694 put_device+0x25/0x30 drivers/base/core.c:1799 klist_devices_put+0x36/0x40 drivers/base/bus.c:827 klist_next+0x264/0x4a0 lib/klist.c:403 next_device drivers/base/bus.c:270 [inline] bus_for_each_dev+0x17e/0x210 drivers/base/bus.c:312 autoload_drivers+0x3b/0x50 sound/core/seq_device.c:117 process_one_work+0x9fb/0x1570 kernel/workqueue.c:2097 worker_thread+0x1e4/0x1350 kernel/workqueue.c:2231 kthread+0x324/0x3f0 kernel/kthread.c:231 ret_from_fork+0x25/0x30 arch/x86/entry/entry_64.S:425
The fix is simply to assure canceling the autoload work at removing the device.
Reported-by: Andrey Konovalov andreyknvl@google.com Tested-by: Andrey Konovalov andreyknvl@google.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de
sound/core/seq_device.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/sound/core/seq_device.c b/sound/core/seq_device.c index c4acf17e9f5e..e40a2cba5002 100644 --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -148,8 +148,10 @@ void snd_seq_device_load_drivers(void) flush_work(&autoload_work); } EXPORT_SYMBOL(snd_seq_device_load_drivers); +#define cancel_autoload_drivers() cancel_work_sync(&autoload_work) #else #define queue_autoload_drivers() /* NOP */ +#define cancel_autoload_drivers() /* NOP */ #endif
/* @@ -159,6 +161,7 @@ static int snd_seq_device_dev_free(struct snd_device *device) { struct snd_seq_device *dev = device->device_data;
cancel_autoload_drivers(); put_device(&dev->dev); return 0;}
2.14.1
participants (2)
-
Andrey Konovalov -
Takashi Iwai