Re: [PATCH] umh: fix UAF when the process is being killed

[Luis Chamberlain]

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?

  Luis