linux-kernel - Re: [PATCH] Close mem leak in error path in mm/hugetlb.c::nr_hugepages_store

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Message-ID: <AANLkTikNx5SG9Z=tUu6tyFRqnR2sLe5NxAjLCJr1UKmq@mail.gmail.com>
Date:	Mon, 20 Dec 2010 10:00:48 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Jesper Juhl <jj@...osbits.net>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] Close mem leak in error path in mm/hugetlb.c::nr_hugepages_store_common()

On Mon, Dec 20, 2010 at 7:10 AM, Jesper Juhl <jj@...osbits.net> wrote:
> Hi,
>
> The NODEMASK_ALLOC macro dynamically allocates memory for its second
> argument ('nodes_allowed' in this context).
> In nr_hugepages_store_common() we may abort early if strict_strtoul()
> fails, but in that case we do not free the memory already allocated to
> 'nodes_allowed', causing a memory leak.
> This patch closes the leak by freeing the memory in the error path.
>
>
> Signed-off-by: Jesper Juhl <jj@...osbits.net>
> ---
>  hugetlb.c |    4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
>  compile tested only
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 8585524..9fdcc35 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1439,8 +1439,10 @@ static ssize_t nr_hugepages_store_common(bool obey_mempolicy,
>        NODEMASK_ALLOC(nodemask_t, nodes_allowed, GFP_KERNEL | __GFP_NORETRY);
>
>        err = strict_strtoul(buf, 10, &count);
> -       if (err)
> +       if (err) {
> +               kfree(nodes_allowed);

Nice catch. But use NODEMASK_FREE. It might be not kmalloced object.



-- 
Kind regards,
Minchan Kim
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