KASAN: use-after-free Write in __vb2_cleanup_fileio

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 7aa823a9 Linux 4.19.51
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=12c6c0c6a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=57222bc62f28e3a6
dashboard link: https://syzkaller.appspot.com/bug?extid=5e99a821fd7364422b3a
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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+5e99a8...@syzkaller.appspotmail.com

Enabling of bearer <udp:syz0> rejected, failed to enable media
Invalid option length (340) for dns_resolver key
==================================================================
BUG: KASAN: use-after-free in __vb2_cleanup_fileio+0x149/0x170
drivers/media/common/videobuf2/videobuf2-core.c:2341
Write of size 4 at addr ffff88809f512900 by task syz-executor.4/8622

CPU: 0 PID: 8622 Comm: syz-executor.4 Not tainted 4.19.51 #23
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+0x172/0x1f0 lib/dump_stack.c:113
print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report mm/kasan/report.c:412 [inline]
kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
__asan_report_store4_noabort+0x17/0x20 mm/kasan/report.c:437
__vb2_cleanup_fileio+0x149/0x170
drivers/media/common/videobuf2/videobuf2-core.c:2341
vb2_core_queue_release+0x20/0x80
drivers/media/common/videobuf2/videobuf2-core.c:2066
vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:671
[inline]
_vb2_fop_release+0x1cf/0x2a0
drivers/media/common/videobuf2/videobuf2-v4l2.c:842
vb2_fop_release+0x75/0xc0
drivers/media/common/videobuf2/videobuf2-v4l2.c:856
vivid_fop_release+0x18e/0x430 drivers/media/platform/vivid/vivid-core.c:474
v4l2_release+0xf9/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:448
__fput+0x2dd/0x8b0 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x412fb1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48
83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48
89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007ffcd362cb70 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 0000000000412fb1
RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 0000000000000000 R08: ffffffffffffffff R09: ffffffffffffffff
R10: 00007ffcd362cc50 R11: 0000000000000293 R12: 00000000007604c8
R13: 00000000001318ac R14: 00000000001318d9 R15: 000000000075c07c

Allocated by task 8633:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc mm/kasan/kasan.c:553 [inline]
kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
kmem_cache_alloc_trace+0x152/0x760 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
__vb2_init_fileio+0x1cb/0xbe0
drivers/media/common/videobuf2/videobuf2-core.c:2250
__vb2_perform_fileio+0xc9a/0x1170
drivers/media/common/videobuf2/videobuf2-core.c:2390
vb2_read+0x3b/0x50 drivers/media/common/videobuf2/videobuf2-core.c:2522
vb2_fop_read+0x212/0x410
drivers/media/common/videobuf2/videobuf2-v4l2.c:897
v4l2_read+0x1cc/0x230 drivers/media/v4l2-core/v4l2-dev.c:317
do_loop_readv_writev fs/read_write.c:701 [inline]
do_loop_readv_writev fs/read_write.c:688 [inline]
do_iter_read+0x490/0x640 fs/read_write.c:925
vfs_readv+0xf0/0x160 fs/read_write.c:987
do_preadv+0x1c4/0x280 fs/read_write.c:1071
__do_sys_preadv fs/read_write.c:1121 [inline]
__se_sys_preadv fs/read_write.c:1116 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1116
do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8633:
save_stack+0x45/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3503 [inline]
kfree+0xcf/0x220 mm/slab.c:3822
__vb2_cleanup_fileio+0x100/0x170
drivers/media/common/videobuf2/videobuf2-core.c:2343
vb2_core_queue_release+0x20/0x80
drivers/media/common/videobuf2/videobuf2-core.c:2066
vb2_queue_release drivers/media/common/videobuf2/videobuf2-v4l2.c:671
[inline]
_vb2_fop_release+0x1cf/0x2a0
drivers/media/common/videobuf2/videobuf2-v4l2.c:842
vb2_fop_release+0x75/0xc0
drivers/media/common/videobuf2/videobuf2-v4l2.c:856
vivid_fop_release+0x18e/0x430 drivers/media/platform/vivid/vivid-core.c:474
v4l2_release+0xf9/0x1a0 drivers/media/v4l2-core/v4l2-dev.c:448
__fput+0x2dd/0x8b0 fs/file_table.c:278
____fput+0x16/0x20 fs/file_table.c:309
task_work_run+0x145/0x1c0 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:193 [inline]
exit_to_usermode_loop+0x273/0x2c0 arch/x86/entry/common.c:167
prepare_exit_to_usermode arch/x86/entry/common.c:198 [inline]
syscall_return_slowpath arch/x86/entry/common.c:271 [inline]
do_syscall_64+0x53d/0x620 arch/x86/entry/common.c:296
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809f512900
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 0 bytes inside of
1024-byte region [ffff88809f512900, ffff88809f512d00)
The buggy address belongs to the page:
page:ffffea00027d4480 count:1 mapcount:0 mapping:ffff88812c3f0ac0
index:0xffff88809f512d80 compound_mapcount: 0
flags: 0x1fffc0000008100(slab|head)
raw: 01fffc0000008100 ffffea0001f36208 ffffea000294dc88 ffff88812c3f0ac0
raw: ffff88809f512d80 ffff88809f512000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809f512800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809f512880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88809f512900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809f512980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809f512a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.