Re: [syzbot] kernel BUG in io_queue_async_work

[Pavel Begunkov]

On 7/13/21 2:19 AM, syzbot wrote:
> 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

#syz test: https://github.com/isilence/linux.git drain_fix_syztest

> 
> ------------[ 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
> 

-- 
Pavel Begunkov