Re: [PATCH] xfs: fix possible NULL dereference

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

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@xxxxxxxxx>
> Signed-off-by: Ben Myers <bpm@xxxxxxx>

Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>

> ---
>  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);
> 
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