Re: [syzbot] kernel BUG in io_queue_async_work

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    7fef2edf sd: don't mess with SD_MINORS for CONFIG_DEBUG_BL..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1575c9b0300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=957eaf08bd3bb8d6
dashboard link: https://syzkaller.appspot.com/bug?extid=d50e4f20cfad4510ec22
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=104c3949d00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=167cc06c300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d50e4f20cfad4510ec22@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
kernel BUG at fs/io_uring.c:1293!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 8139 Comm: kworker/1:3 Tainted: G        W         5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events io_fallback_req_func
RIP: 0010:io_queue_async_work+0x539/0x5f0 fs/io_uring.c:1293
Code: 89 be 89 00 00 00 48 c7 c7 40 53 9a 89 c6 05 de 38 78 0b 01 e8 72 6b 08 07 e9 6e ff ff ff e8 ee 68 95 ff 0f 0b e8 e7 68 95 ff <0f> 0b e8 e0 68 95 ff 0f 0b e9 1a fd ff ff e8 34 0f db ff e9 47 fb
RSP: 0018:ffffc9000c627ba8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802d256000 RCX: 0000000000000000
RDX: ffff888030f4e180 RSI: ffffffff81df55c9 RDI: ffff88802ef66a50
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000019
R10: ffffffff81df517c R11: 000000000000000f R12: ffff8880441eb6c0
R13: 0000000000000019 R14: ffff88802d2560b0 R15: ffff8880441eb718
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000049a01d CR3: 00000000396af000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __io_queue_sqe+0x913/0xf10 fs/io_uring.c:6448
 io_req_task_submit+0x100/0x120 fs/io_uring.c:2020
 io_fallback_req_func+0x81/0xb0 fs/io_uring.c:2441
 process_one_work+0x98d/0x1630 kernel/workqueue.c:2276
 worker_thread+0x658/0x11f0 kernel/workqueue.c:2422
 kthread+0x3e5/0x4d0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Modules linked in:
---[ end trace aa15edd5dcdbd7e3 ]---
RIP: 0010:io_queue_async_work+0x539/0x5f0 fs/io_uring.c:1293
Code: 89 be 89 00 00 00 48 c7 c7 40 53 9a 89 c6 05 de 38 78 0b 01 e8 72 6b 08 07 e9 6e ff ff ff e8 ee 68 95 ff 0f 0b e8 e7 68 95 ff <0f> 0b e8 e0 68 95 ff 0f 0b e9 1a fd ff ff e8 34 0f db ff e9 47 fb
RSP: 0018:ffffc9000c627ba8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802d256000 RCX: 0000000000000000
RDX: ffff888030f4e180 RSI: ffffffff81df55c9 RDI: ffff88802ef66a50
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000019
R10: ffffffff81df517c R11: 000000000000000f R12: ffff8880441eb6c0
R13: 0000000000000019 R14: ffff88802d2560b0 R15: ffff8880441eb718
FS:  0000000000000000(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000444 CR3: 0000000042660000 CR4: 00000000001506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400