linux-kernel - Re: [PATCH] kernel/kmod: fix use-after-free of the sub

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Date:	Fri, 17 Oct 2014 09:04:52 +0200
From:	Martin Schwidefsky <schwidefsky@...ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] kernel/kmod: fix use-after-free of the
 sub_infostructure

On Thu, 16 Oct 2014 23:58:34 +0200
Oleg Nesterov <oleg@...hat.com> wrote:

> On 10/17, Tetsuo Handa wrote:
> >
> > Ah, I see. Here is a draft of an updated patch.
> 
> Do you mean this part
> 
> 	>  	sub_info->retval = retval;
> 	> +	/* wait_for_helper() will call umh_complete() if UMH_WAIT_PROC. */
> 	> +	if (wait != UMH_WAIT_PROC)
> 	> +		umh_complete(sub_info);
> 	> +	if (!retval)
> 	> +		return 0;
> 	>  	do_exit(0);
> 	>  }
> 
> ?
> 
> Personally I agree, this looks a bit better to me. But this is cosmetic
> and subjective, I leave this to Martin ;)

I don't mind the different code order. As you seem to prefer the above I
use your version.
 
> I also agree that the changelog could mention exec_mmap. Plus a comment
> about UMH_NO_WAIT && sub_info->complete == NULL. So yes, perhaps v2 makes
> sense if Martin agrees.

Ok, this part is a bit tricky and deserves a comment. I'll create one
and send v2.

-- 
blue skies,
   Martin.

"Reality continues to ruin my life." - Calvin.

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