linux-kernel - Re: [PATCH] ublk_drv: fix NULL pointer dereference in ublk_ctrl_start

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Date: Sat, 8 Jun 2024 14:44:03 +0800
From: Li Nan <linan666@...weicloud.com>
To: Changhui Zhong <czhong@...hat.com>, Li Nan <linan666@...weicloud.com>
Cc: Ming Lei <ming.lei@...hat.com>, axboe@...nel.dk,
 ZiyangZhang@...ux.alibaba.com, linux-block@...r.kernel.org,
 linux-kernel@...r.kernel.org, yukuai3@...wei.com, yi.zhang@...wei.com,
 houtao1@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH] ublk_drv: fix NULL pointer dereference in
 ublk_ctrl_start_recovery()



在 2024/6/6 21:43, Changhui Zhong 写道:
> On Thu, Jun 6, 2024 at 4:05 PM Li Nan <linan666@...weicloud.com> wrote:
>>
>>
>>
>> 在 2024/6/6 12:48, Changhui Zhong 写道:
>>
>> [...]
>>
>>>>
>>>> Hi Changhui,
>>>>
>>>> The hang is actually expected because recovery fails.
>>>>
>>>> Please pull the latest ublksrv and check if the issue can still be
>>>> reproduced:
>>>>
>>>> https://github.com/ublk-org/ublksrv
>>>>
>>>> BTW, one ublksrv segfault and two test cleanup issues are fixed.
>>>>
>>>> Thanks,
>>>> Ming
>>>>
>>>
>>> Hi,Ming and Nan
>>>
>>> after applying the new patch and pulling the latest ublksrv,
>>> I ran the test for 4 hours and did not observe any task hang.
>>> the test results looks good！
>>>
>>> Thanks，
>>> Changhui
>>>
>>>
>>> .
>>
>> Thanks for you test!
>>
>> However, I got a NULL pointer dereference bug with ublksrv. It is not
>> introduced by this patch. It seems io was issued after deleting disk. And
>> it can be reproduced by:
>>
>>     while true; do make test T=generic/004; done
>>
> 
> Hi,Nan
> 
> I can not reproduce this issue with repo
> https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/log/?h=for-next
> ,
> which kernel repo do you using for test?
> 
> Thanks,
> Changhui
> 

I tested with the latest block code, commit
2ab79514109578fc4b6df90633d500cf281eb689, this issue also can be
reproduced.

The space of the root path has been filled up by
ublksrv(tests/tmpublk_loop_data_xxx), which may the issue be related to this?

-- 
Thanks,
Nan