linux-kernel - Re: [PATCH] xfs: fix potential memory leak in xfs_bmap_add

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Message-ID: <20220706222059.GL227878@dread.disaster.area>
Date:   Thu, 7 Jul 2022 08:20:59 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Jianglei Nie <niejianglei2021@....com>
Cc:     djwong@...nel.org, dchinner@...hat.com, chandan.babu@...cle.com,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs: fix potential memory leak in xfs_bmap_add_attrfork()

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@....com>
> ---
>  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@...morbit.com