linux-kernel - Re: [PATCH] xfs: fix possible NULL dereference

Open Source and information security mailing list archives

Date:	Wed, 30 Oct 2013 15:08:12 -0500
From:	Eric Sandeen <sandeen@...deen.net>
To:	Ben Myers <bpm@....com>,
	Geyslan Gregório Bem <geyslan@...il.com>
CC:	Alex Elder <elder@...nel.org>,
	open list <linux-kernel@...r.kernel.org>,
	XFS FILESYSTEM <xfs@....sgi.com>
Subject: Re: [PATCH] xfs: fix possible NULL dereference

On 10/23/13 3:34 PM, Ben Myers wrote:

> xfs: fix possible NULL dereference in xlog_verify_iclog
> 
> In xlog_verify_iclog a debug check of the incore log buffers prints an
> error if icptr is null and then goes on to dereference the pointer
> regardless.  Convert this to an assert so that the intention is clear.
> This was reported by Coverty.
> 
> Reported-by: Geyslan G. Bem <geyslan@...il.com>
> Signed-off-by: Ben Myers <bpm@....com>

Reviewed-by: Eric Sandeen <sandeen@...hat.com>

> ---
>  fs/xfs/xfs_log.c |    8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> Index: b/fs/xfs/xfs_log.c
> ===================================================================
> --- a/fs/xfs/xfs_log.c	2013-10-23 14:52:47.875216875 -0500
> +++ b/fs/xfs/xfs_log.c	2013-10-23 14:53:53.775245830 -0500
> @@ -3714,11 +3714,9 @@ xlog_verify_iclog(
>  	/* check validity of iclog pointers */
>  	spin_lock(&log->l_icloglock);
>  	icptr = log->l_iclog;
> -	for (i=0; i < log->l_iclog_bufs; i++) {
> -		if (icptr == NULL)
> -			xfs_emerg(log->l_mp, "%s: invalid ptr", __func__);
> -		icptr = icptr->ic_next;
> -	}
> +	for (i=0; i < log->l_iclog_bufs; i++, icptr = icptr->ic_next)
> +      		ASSERT(icptr);
> +
>  	if (icptr != log->l_iclog)
>  		xfs_emerg(log->l_mp, "%s: corrupt iclog ring", __func__);
>  	spin_unlock(&log->l_icloglock);
> 
> _______________________________________________
> xfs mailing list
> xfs@....sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs
> 

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