Hello,

syzbot found the following crash on:

HEAD commit: 76bb8b05 Merge tag 'kbuild-v5.5' of git://git.kernel.org/p.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1416a90ee00000 kernel config: https://syzkaller.appspot.com/x/.config?x=dd226651cb0f364b dashboard link: https://syzkaller.appspot.com/bug?extid=f153bde47a62e0b05f83 compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10fe9e41e00000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1522042ae00000

The bug was bisected to:

commit 65766ee0bf7fe8b3be80e2e1c3ef54ad59b29476 Author: Takashi Iwai tiwai@suse.de Date: Fri Nov 9 10:59:45 2018 +0000

ALSA: oss: Use kvzalloc() for local buffer allocations

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1727742ae00000 final crash: https://syzkaller.appspot.com/x/report.txt?x=14a7742ae00000 console output: https://syzkaller.appspot.com/x/log.txt?x=10a7742ae00000

IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+f153bde47a62e0b05f83@syzkaller.appspotmail.com Fixes: 65766ee0bf7f ("ALSA: oss: Use kvzalloc() for local buffer allocations")

================================================================== BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:380 [inline] BUG: KASAN: slab-out-of-bounds in do_convert sound/core/oss/linear.c:48 [inline] BUG: KASAN: slab-out-of-bounds in convert sound/core/oss/linear.c:81 [inline] BUG: KASAN: slab-out-of-bounds in linear_transfer sound/core/oss/linear.c:110 [inline] BUG: KASAN: slab-out-of-bounds in linear_transfer+0x6de/0x970 sound/core/oss/linear.c:88 Read of size 1 at addr ffff8880a3eb5540 by task syz-executor567/8984

CPU: 0 PID: 8984 Comm: syz-executor567 Not tainted 5.4.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374 __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:638 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x134/0x1a0 mm/kasan/generic.c:192 memcpy+0x24/0x50 mm/kasan/common.c:124 memcpy include/linux/string.h:380 [inline] do_convert sound/core/oss/linear.c:48 [inline] convert sound/core/oss/linear.c:81 [inline] linear_transfer sound/core/oss/linear.c:110 [inline] linear_transfer+0x6de/0x970 sound/core/oss/linear.c:88 snd_pcm_plug_read_transfer+0x197/0x2e0 sound/core/oss/pcm_plugin.c:651 snd_pcm_oss_read2+0x1f0/0x3f0 sound/core/oss/pcm_oss.c:1460 snd_pcm_oss_read1 sound/core/oss/pcm_oss.c:1517 [inline] snd_pcm_oss_read+0x548/0x6a0 sound/core/oss/pcm_oss.c:2741 __vfs_read+0x8a/0x110 fs/read_write.c:425 vfs_read+0x1f0/0x440 fs/read_write.c:461 ksys_read+0x14f/0x290 fs/read_write.c:587 __do_sys_read fs/read_write.c:597 [inline] __se_sys_read fs/read_write.c:595 [inline] __x64_sys_read+0x73/0xb0 fs/read_write.c:595 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x445a99 Code: e8 dc bd 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb 11 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f2955880ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000445a99 RDX: 0000000000001000 RSI: 0000000020000380 RDI: 0000000000000003 RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c R13: 00007ffd9643eb4f R14: 00007f29558819c0 R15: 20c49ba5e353f7cf

Allocated by task 8984: save_stack+0x23/0x90 mm/kasan/common.c:71 set_track mm/kasan/common.c:79 [inline] __kasan_kmalloc mm/kasan/common.c:512 [inline] __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:485 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:526 __do_kmalloc_node mm/slab.c:3616 [inline] __kmalloc_node+0x4e/0x70 mm/slab.c:3623 kmalloc_node include/linux/slab.h:579 [inline] kvmalloc_node+0x68/0x100 mm/util.c:574 kvmalloc include/linux/mm.h:655 [inline] kvzalloc include/linux/mm.h:663 [inline] snd_pcm_plugin_alloc+0x585/0x770 sound/core/oss/pcm_plugin.c:70 snd_pcm_plug_alloc+0x146/0x330 sound/core/oss/pcm_plugin.c:129 snd_pcm_oss_change_params_locked+0x210f/0x3750 sound/core/oss/pcm_oss.c:1024 snd_pcm_oss_change_params+0x7b/0xd0 sound/core/oss/pcm_oss.c:1087 snd_pcm_oss_get_active_substream+0x136/0x190 sound/core/oss/pcm_oss.c:1104 snd_pcm_oss_get_rate sound/core/oss/pcm_oss.c:1754 [inline] snd_pcm_oss_set_rate sound/core/oss/pcm_oss.c:1746 [inline] snd_pcm_oss_ioctl+0x1794/0x33a0 sound/core/oss/pcm_oss.c:2593 vfs_ioctl fs/ioctl.c:47 [inline] file_ioctl fs/ioctl.c:545 [inline] do_vfs_ioctl+0x977/0x14e0 fs/ioctl.c:732 ksys_ioctl+0xab/0xd0 fs/ioctl.c:749 __do_sys_ioctl fs/ioctl.c:756 [inline] __se_sys_ioctl fs/ioctl.c:754 [inline] __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:754 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0: (stack is not available)

The buggy address belongs to the object at ffff8880a3eb5500 which belongs to the cache kmalloc-64 of size 64 The buggy address is located 0 bytes to the right of 64-byte region [ffff8880a3eb5500, ffff8880a3eb5540) The buggy address belongs to the page: page:ffffea00028fad40 refcount:1 mapcount:0 mapping:ffff8880aa400380 index:0x0 raw: 00fffe0000000200 ffffea00027da7c8 ffff8880aa401348 ffff8880aa400380 raw: 0000000000000000 ffff8880a3eb5000 0000000100000020 0000000000000000 page dumped because: kasan: bad access detected

Memory state around the buggy address: ffff8880a3eb5400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880a3eb5480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8880a3eb5500: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc

^ ffff8880a3eb5580: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc ffff8880a3eb5600: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc ==================================================================

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