Re: [PATCH] xfs: fix potential memory leak in xfs_bmap_add_attrfork()

[Dave Chinner]

On Wed, Jul 06, 2022 at 04:22:37PM +0800, Jianglei Nie wrote:
> xfs_bmap_add_attrfork() allocates a memory chunk for ip->i_afp with
> xfs_ifork_alloc(). When some error occurs, the function goto trans_cancel;
> without releasing the ip->i_afp, which will lead to a memory leak.

Where does it leak? Do you ahve a KASAN report?

> We should release the ip->i_afp with kmem_cache_free() and set "ip->i_afp
> = NULL" if ip->i_afp is not NULL pointer.
> 
> Signed-off-by: Jianglei Nie <niejianglei2021@xxxxxxx>
> ---
>  fs/xfs/libxfs/xfs_bmap.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 6833110d1bd4..0c99726c0968 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -1088,6 +1088,10 @@ xfs_bmap_add_attrfork(
>  trans_cancel:
>  	xfs_trans_cancel(tp);
>  	xfs_iunlock(ip, XFS_ILOCK_EXCL);
> +	if (ip->i_afp) {
> +		kmem_cache_free(xfs_ifork_cache, ip->i_afp);
> +		ip->a_afp = NULL;
                    ^^^^^

Please compile and test your changes before proposing them for
inclusion.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx