linux-kernel - Re: [PATCH 1/2] xfs: zero initialize highstale and lowstale in xfs_dir2_leaf

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 12 Mar 2019 09:22:02 -0500
From:   Bill O'Donnell <billodo@...hat.com>
To:     "Darrick J. Wong" <darrick.wong@...cle.com>
Cc:     linux-xfs@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>,
        linux-kernel@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH 1/2] xfs: zero initialize highstale and lowstale in
 xfs_dir2_leaf_addname

On Mon, Mar 11, 2019 at 09:19:48AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@...cle.com>
> 
> Smatch complains about the following:
> 
> fs/xfs/libxfs/xfs_dir2_leaf.c:848 xfs_dir2_leaf_addname() error:
> uninitialized symbol 'lowstale'.
> 
> fs/xfs/libxfs/xfs_dir2_leaf.c:849 xfs_dir2_leaf_addname() error:
> uninitialized symbol 'highstale'.
> 
> I don't think there's any incorrect behavior associated with the
> uninitialized variable, but as the author of the previous zero-init
> patch points out, it's best not to be passing around pointers to
> uninitialized stack areas.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>

Reviewed-by: Bill O'Donnell <billodo@...hat.com>

> ---
>  fs/xfs/libxfs/xfs_dir2_leaf.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_dir2_leaf.c b/fs/xfs/libxfs/xfs_dir2_leaf.c
> index 9a3767818c50..2abf945e5844 100644
> --- a/fs/xfs/libxfs/xfs_dir2_leaf.c
> +++ b/fs/xfs/libxfs/xfs_dir2_leaf.c
> @@ -574,7 +574,7 @@ xfs_dir2_leaf_addname(
>  	xfs_dir2_data_unused_t	*dup;		/* data unused entry */
>  	int			error;		/* error return value */
>  	int			grown;		/* allocated new data block */
> -	int			highstale;	/* index of next stale leaf */
> +	int			highstale = 0;	/* index of next stale leaf */
>  	int			i;		/* temporary, index */
>  	int			index;		/* leaf table position */
>  	struct xfs_buf		*lbp;		/* leaf's buffer */
> @@ -583,7 +583,7 @@ xfs_dir2_leaf_addname(
>  	xfs_dir2_leaf_entry_t	*lep;		/* leaf entry table pointer */
>  	int			lfloglow;	/* low leaf logging index */
>  	int			lfloghigh;	/* high leaf logging index */
> -	int			lowstale;	/* index of prev stale leaf */
> +	int			lowstale = 0;	/* index of prev stale leaf */
>  	xfs_dir2_leaf_tail_t	*ltp;		/* leaf tail pointer */
>  	int			needbytes;	/* leaf block bytes needed */
>  	int			needlog;	/* need to log data header */