APPLIED/CMT[F]: [SRU Focal, Focal/oem-5.6] xfs: fix boundary test in xfs_attr_shortform_verify
ian.may at canonical.com
Thu Sep 17 23:27:20 UTC 2020
This patch was applied in the following patchset:
Focal update: v5.4.64 upstream stable release
On 2020-09-16 14:50:15 , Thadeu Lima de Souza Cascardo wrote:
> From: Eric Sandeen <sandeen at redhat.com>
> The boundary test for the fixed-offset parts of xfs_attr_sf_entry in
> xfs_attr_shortform_verify is off by one, because the variable array
> at the end is defined as nameval not nameval.
> Hence we need to subtract 1 from the calculation.
> This can be shown by:
> and verifications will fail when it's written to disk.
> This only matters for a last attribute which has a single-byte name
> and no value, otherwise the combination of namelen & valuelen will
> push endp further out and this test won't fail.
> Fixes: 1e1bbd8e7ee06 ("xfs: create structure verifier function for shortform xattrs")
> Signed-off-by: Eric Sandeen <sandeen at redhat.com>
> Reviewed-by: Darrick J. Wong <darrick.wong at oracle.com>
> Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
> Reviewed-by: Christoph Hellwig <hch at lst.de>
> (cherry picked from commit f4020438fab05364018c91f7e02ebdd192085933)
> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
> fs/xfs/libxfs/xfs_attr_leaf.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
> index fed537a4353d..54c412549edf 100644
> --- a/fs/xfs/libxfs/xfs_attr_leaf.c
> +++ b/fs/xfs/libxfs/xfs_attr_leaf.c
> @@ -1010,8 +1010,10 @@ xfs_attr_shortform_verify(
> * struct xfs_attr_sf_entry has a variable length.
> * Check the fixed-offset parts of the structure are
> * within the data buffer.
> + * xfs_attr_sf_entry is defined with a 1-byte variable
> + * array at the end, so we must subtract that off.
> - if (((char *)sfep + sizeof(*sfep)) >= endp)
> + if (((char *)sfep + sizeof(*sfep) - 1) >= endp)
> return __this_address;
> /* Don't allow names with known bad length. */
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