Re: [syzbot] kernel BUG in io_queue_async_work

From: Pavel Begunkov <asml.silence@gmail.com>
To: syzbot <syzbot+d50e4f20cfad4510ec22@syzkaller.appspotmail.com>,
	axboe@kernel.dk, io-uring@vger.kernel.org,
	linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] kernel BUG in io_queue_async_work
Date: Mon, 12 Jul 2021 14:00:07 +0100	[thread overview]
Message-ID: <34411b70-e29f-3631-a81c-df20c2964211@gmail.com> (raw)
In-Reply-To: <000000000000d0615505c6e9bd7f@google.com>

On 7/12/21 10:28 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    e2f74b13 Add linux-next specific files for 20210708
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14fc6fb4300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=59e1e3bbc3afca75
> dashboard link: https://syzkaller.appspot.com/bug?extid=d50e4f20cfad4510ec22
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+d50e4f20cfad4510ec22@syzkaller.appspotmail.com

[...]

>  __io_queue_sqe+0x913/0xf10 fs/io_uring.c:6444

Shouldn't have got here from fallback, so very similar to a bug fixed
by an already sent "io_uring: use right task for exiting checks"

>  io_req_task_submit+0x100/0x120 fs/io_uring.c:2020
>  io_fallback_req_func+0x81/0xb0 fs/io_uring.c:2437
>  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 4d51acadba583174 ]---
> RIP: 0010:io_queue_async_work+0x539/0x5f0 fs/io_uring.c:1293
> Code: 89 be 89 00 00 00 48 c7 c7 00 8a 9a 89 c6 05 28 5f 77 0b 01 e8 be e9 06 07 e9 6e ff ff ff e8 be 1e 95 ff 0f 0b e8 b7 1e 95 ff <0f> 0b e8 b0 1e 95 ff 0f 0b e9 1a fd ff ff e8 d4 2f db ff e9 47 fb
> RSP: 0018:ffffc900032efba8 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffff88802840c800 RCX: 0000000000000000
> RDX: ffff888082e09c80 RSI: ffffffff81e07d49 RDI: ffff8880224da498
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000043736500
> R10: ffffffff81e222ff R11: 0000000000000000 R12: ffff8880782e78c0
> R13: 0000000000000019 R14: ffff88802840c8b0 R15: ffff8880782e7918
> FS:  0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f3dee45e000 CR3: 000000002dd4e000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 

-- 
Pavel Begunkov