KASAN: use-after-free Read in io_wqe_worker

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 98477740 Merge branch 'rcu/urgent' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=153e929b900000
kernel config: https://syzkaller.appspot.com/x/.config?x=af502ec9a451c9fc
dashboard link: https://syzkaller.appspot.com/bug?extid=9af99580130003da82b1
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14138009900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17d0f809900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9af995...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x92/0x2ae0 kernel/locking/lockdep.c:4311
Read of size 8 at addr ffff88821ae5f818 by task io_wqe_worker-0/11054

CPU: 1 PID: 11054 Comm: io_wqe_worker-0 Not tainted 5.9.0-rc6-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+0x1d6/0x29e lib/dump_stack.c:118
print_address_description+0x66/0x620 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report+0x132/0x1d0 mm/kasan/report.c:530
__lock_acquire+0x92/0x2ae0 kernel/locking/lockdep.c:4311
lock_acquire+0x148/0x720 kernel/locking/lockdep.c:5029
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0xa6/0xc0 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:379 [inline]
io_wqe_worker+0x756/0x810 fs/io-wq.c:589
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Allocated by task 11048:
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461
kmem_cache_alloc_node_trace+0x1f7/0x2a0 mm/slab.c:3594
kmalloc_node include/linux/slab.h:572 [inline]
kzalloc_node include/linux/slab.h:677 [inline]
io_wq_create+0x295/0x880 fs/io-wq.c:1064
io_init_wq_offload fs/io_uring.c:7432 [inline]
io_sq_offload_start fs/io_uring.c:7504 [inline]
io_uring_create fs/io_uring.c:8625 [inline]
io_uring_setup fs/io_uring.c:8694 [inline]
__do_sys_io_uring_setup fs/io_uring.c:8700 [inline]
__se_sys_io_uring_setup+0x18ed/0x2a00 fs/io_uring.c:8697
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 128:
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_set_track+0x3d/0x70 mm/kasan/common.c:56
kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355
__kasan_slab_free+0xdd/0x110 mm/kasan/common.c:422
__cache_free mm/slab.c:3418 [inline]
kfree+0x113/0x200 mm/slab.c:3756
__io_wq_destroy fs/io-wq.c:1138 [inline]
io_wq_destroy+0x470/0x510 fs/io-wq.c:1146
io_finish_async fs/io_uring.c:6836 [inline]
io_ring_ctx_free fs/io_uring.c:7870 [inline]
io_ring_exit_work+0x195/0x520 fs/io_uring.c:7954
process_one_work+0x789/0xfc0 kernel/workqueue.c:2269
worker_thread+0xaa4/0x1460 kernel/workqueue.c:2415
kthread+0x37e/0x3a0 drivers/block/aoe/aoecmd.c:1234
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

The buggy address belongs to the object at ffff88821ae5f800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 24 bytes inside of
1024-byte region [ffff88821ae5f800, ffff88821ae5fc00)
The buggy address belongs to the page:
page:000000008e41b1c2 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x21ae5f
flags: 0x57ffe0000000200(slab)
raw: 057ffe0000000200 ffffea00086a10c8 ffffea00085d1848 ffff8880aa440700
raw: 0000000000000000 ffff88821ae5f000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88821ae5f700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88821ae5f780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88821ae5f800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88821ae5f880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88821ae5f900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[Jens Axboe]

Hillf, you've been looking at this one, care to spend a bit of time on it
and pull it to completion?

--
Jens Axboe

[Jens Axboe]

#syz test: git://git.kernel.dk/linux-block io_uring-5.9

--
Jens Axboe

[Jens Axboe]

#syz test: git://git.kernel.dk/linux-block.git 41d5f92f60a61e264dafbada79175dad0bc60c5b

--
Jens Axboe

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+9af995...@syzkaller.appspotmail.com

Tested on:

commit: 41d5f92f io-wq: fix worker refcount race
git tree: git://git.kernel.dk/linux-block io_uring-5.9
kernel config: https://syzkaller.appspot.com/x/.config?x=d31db37354c30905

dashboard link: https://syzkaller.appspot.com/bug?extid=9af99580130003da82b1
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

Note: testing is done by a robot and is best-effort only.

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+9af995...@syzkaller.appspotmail.com

Tested on:

commit: 41d5f92f io-wq: fix worker refcount race

git tree: git://git.kernel.dk/linux-block.git