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From:   Schspa Shi <schspa@gmail.com>
To:     Luis Chamberlain <mcgrof@kernel.org>
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Subject: Re: [PATCH] umh: fix UAF when the process is being killed
Date:   Wed, 14 Dec 2022 10:28:11 +0800
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Luis Chamberlain <mcgrof@kernel.org> writes:

> On Mon, Dec 12, 2022 at 09:38:31PM +0800, Schspa Shi wrote:
>> I'd like to upload a V2 patch with the new solution if you prefer the
>> following way.
>> 
>> diff --git a/kernel/umh.c b/kernel/umh.c
>> index 850631518665..8023f11fcfc0 100644
>> --- a/kernel/umh.c
>> +++ b/kernel/umh.c
>> @@ -452,6 +452,11 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait)
>>                 /* umh_complete() will see NULL and free sub_info */
>>                 if (xchg(&sub_info->complete, NULL))
>>                         goto unlock;
>> +               /*
>> +                * kthreadd (or new kernel thread) will call complete()
>> +                * shortly.
>> +                */
>> +               wait_for_completion(&done);
>>         }
>
> Yes much better. Did you verify it fixes the splat found by the bots?
>

Yes, it will fix it.

>   Luis


-- 
BRs
Schspa Shi