Re: [PATCH v4] xfs_db: release ip resource before returning from get_next_unlinked()

Darrick J. Wong
2024-08-09T16:23:27Z

On Fri, Aug 09, 2024 at 11:15:11AM -0500, Bill O'Donnell wrote:
> Fix potential memory leak in function get_next_unlinked(). Call
> libxfs_irele(ip) before exiting.
>
> Details:
> Error: RESOURCE_LEAK (CWE-772):
> xfsprogs-6.5.0/db/iunlink.c:51:2: alloc_arg: "libxfs_iget" allocates memory that is stored into "ip".
> xfsprogs-6.5.0/db/iunlink.c:68:2: noescape: Resource "&ip->i_imap" is not freed or pointed-to in "libxfs_imap_to_bp".
> xfsprogs-6.5.0/db/iunlink.c:76:2: leaked_storage: Variable "ip" going out of scope leaks the storage it points to.
> # 74| libxfs_buf_relse(ino_bp);
> # 75|
> # 76|-> return ret;
> # 77| bad:
> # 78| dbprintf(_("AG %u agino %u: %s\n"), agno, agino, strerror(error));
>
> Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
> ---
> v2: cover error case.
> v3: fix coverage to not release unitialized variable.
> v4: add logic to cover error case when ip is not attained.
> ---
> db/iunlink.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/db/iunlink.c b/db/iunlink.c
> index d87562e3..98d1effc 100644
> --- a/db/iunlink.c
> +++ b/db/iunlink.c
> @@ -49,8 +49,12 @@ get_next_unlinked(
>
> ino = XFS_AGINO_TO_INO(mp, agno, agino);
> error = -libxfs_iget(mp, NULL, ino, 0, &ip);
> - if (error)
> - goto bad;
> + if (error) {
> + if (ip)
> + goto bad_rele;

When does libxfs_iget return nonzero and a non-NULL ip? Wouldn't 'goto
bad' suffice here?

--D

> + else
> + goto bad;
> + }
>
> if (verbose) {
> xfs_filblks_t blocks, rtblks = 0;
> @@ -67,13 +71,16 @@ get_next_unlinked(
>
> error = -libxfs_imap_to_bp(mp, NULL, &ip->i_imap, &ino_bp);
> if (error)
> - goto bad;
> + goto bad_rele;
>
> dip = xfs_buf_offset(ino_bp, ip->i_imap.im_boffset);
> ret = be32_to_cpu(dip->di_next_unlinked);
> libxfs_buf_relse(ino_bp);
> + libxfs_irele(ip);
>
> return ret;
> +bad_rele:
> + libxfs_irele(ip);
> bad:
> dbprintf(_("AG %u agino %u: %s\n"), agno, agino, strerror(error));
> return NULLAGINO;
> --
> 2.46.0
>
>