linux-kernel - Re: [PATCH] pstore: skip zero size persistent ram buffer in traverse

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Date:	Mon, 3 Mar 2014 11:46:52 -0800
From:	Kees Cook <keescook@...omium.org>
To:	shuox.liu@...el.com
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Tony Luck <tony.luck@...el.com>,
	Colin Cross <ccross@...roid.com>,
	Anton Vorontsov <anton@...msg.org>,
	yanmin_zhang@...ux.intel.com
Subject: Re: [PATCH] pstore: skip zero size persistent ram buffer in traverse

On Thu, Feb 27, 2014 at 10:38 PM,  <shuox.liu@...el.com> wrote:
> From: Liu ShuoX <shuox.liu@...el.com>
>
> In ramoops_pstore_read, a valid prz pointer with zero size buffer will
> break traverse of all persistent ram buffers. The latter buffer might
> be lost.
>
> Signed-off-by: Liu ShuoX <shuox.liu@...el.com>
> ---
>  fs/pstore/ram.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index a5d0cab..929ea55 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -119,12 +119,12 @@ ramoops_get_next_prz(struct persistent_ram_zone *przs[], uint *c, uint max,
>
>         prz = przs[i];
>
> -       if (update) {
> -               /* Update old/shadowed buffer. */
> +       /* Update old/shadowed buffer. */
> +       if (update)
>                 persistent_ram_save_old(prz);
> -               if (!persistent_ram_old_size(prz))
> -                       return NULL;
> -       }
> +
> +       if (!persistent_ram_old_size(prz))
> +               return NULL;
>
>         *typep = type;
>         *id = i;

Good catch; this change makes sense to me.

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

-- 
Kees Cook
Chrome OS Security
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