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Message-ID: <e4487267-effa-32dc-1199-db439dd3bf03@gmail.com>
Date:   Tue, 11 Oct 2022 02:03:02 +0100
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Subject: Re: BUG: corrupted list in io_poll_task_func
To:     Wei Chen <harperchen1110@gmail.com>, axboe@kernel.dk,
        io-uring@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org
References: <CAO4mrffiwEOr2tC+LXnjzP7QZ56M+V3o87K43Y7m6-rvHfwjwA@mail.gmail.com>
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From:   Pavel Begunkov <asml.silence@gmail.com>
In-Reply-To: <CAO4mrffiwEOr2tC+LXnjzP7QZ56M+V3o87K43Y7m6-rvHfwjwA@mail.gmail.com>
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On 10/10/22 13:41, Wei Chen wrote:
> Dear Linux Developer,
> 
> Recently when using our tool to fuzz kernel, the following crash was triggered:
> 
> HEAD commit: c5eb0a61238d Linux 5.18-rc6
> git tree: upstream
> compiler: clang 12.0.0
> console output:
> https://drive.google.com/file/d/1Obzlp9wrLFx9BogwmOHhmnQqyMYa2z_k/view?usp=sharing
> kernel config: https://drive.google.com/file/d/12fNP5UArsFqTi2jjGomWuCk5evtgU0Gu/view?usp=sharing

It's hard to tell anything as it's rc6 and we have a couple of
poll fixes backported to stable 5.18. Would be great if you tell
whether you see it with a stable kernel. Also a repro would
help if it finds it. Thanks


> 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: Wei Chen <harperchen1110@gmail.com>
> 
> list_del corruption. prev->next should be ffff88810ec0ae30, but was
> ffff888114119218. (prev=ffff888114119218)
> ------------[ cut here ]------------
> kernel BUG at lib/list_debug.c:53!
> invalid opcode: 0000 [#1] PREEMPT SMP
> CPU: 0 PID: 20805 Comm: iou-sqp-20802 Not tainted 5.18.0-rc6 #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.13.0-1ubuntu1.1 04/01/2014
> RIP: 0010:__list_del_entry_valid+0xa7/0xc0
> Code: 48 c7 c7 54 12 3f 83 4c 89 fe 48 89 da 31 c0 e8 89 e0 21 01 0f
> 0b 48 c7 c7 6f d7 48 83 4c 89 fe 4c 89 e1 31 c0 e8 73 e0 21 01 <0f> 0b
> 48 c7 c7 17 b4 42 83 4c 89 fe 4c 89 f1 31 c0 e8 5d e0 21 01
> RSP: 0018:ffffc900026dbb58 EFLAGS: 00010046
> RAX: 000000000000006d RBX: dead000000000122 RCX: 6101d1e720e71900
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffff88810ec0ae08 R08: ffffffff8115f303 R09: 0000000000000000
> R10: 0001ffffffffffff R11: 000188813bc1b460 R12: ffff888114119218
> R13: ffff88810ec0ae00 R14: ffff888114119218 R15: ffff88810ec0ae30
> FS:  00007f1e57534700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f1e574afdb8 CR3: 00000001394b3000 CR4: 0000000000750ef0
> DR0: 0000000020000140 DR1: 0000000020000440 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
> PKRU: 55555554
> Call Trace:
>   <TASK>
>   io_poll_task_func+0x1ca/0x4f0
>   tctx_task_work+0x808/0xae0
>   task_work_run+0x8e/0x110
>   get_signal+0x13c6/0x1520
>   io_sq_thread+0x382/0xbd0
>   ret_from_fork+0x1f/0x30
>   </TASK>
> Modules linked in:
> Dumping ftrace buffer:
>     (ftrace buffer empty)
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:__list_del_entry_valid+0xa7/0xc0
> Code: 48 c7 c7 54 12 3f 83 4c 89 fe 48 89 da 31 c0 e8 89 e0 21 01 0f
> 0b 48 c7 c7 6f d7 48 83 4c 89 fe 4c 89 e1 31 c0 e8 73 e0 21 01 <0f> 0b
> 48 c7 c7 17 b4 42 83 4c 89 fe 4c 89 f1 31 c0 e8 5d e0 21 01
> RSP: 0018:ffffc900026dbb58 EFLAGS: 00010046
> RAX: 000000000000006d RBX: dead000000000122 RCX: 6101d1e720e71900
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
> RBP: ffff88810ec0ae08 R08: ffffffff8115f303 R09: 0000000000000000
> R10: 0001ffffffffffff R11: 000188813bc1b460 R12: ffff888114119218
> R13: ffff88810ec0ae00 R14: ffff888114119218 R15: ffff88810ec0ae30
> FS:  00007f1e57534700(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f1e574afdb8 CR3: 00000001394b3000 CR4: 0000000000750ef0
> DR0: 0000000020000140 DR1: 0000000020000440 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
> PKRU: 55555554
> 
> Best,
> Wei

-- 
Pavel Begunkov