Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.8 074/186] xfs: fix boundary test in xfs_attr_shortform_verify | Date | Tue, 8 Sep 2020 17:23:36 +0200 |
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From: Eric Sandeen <sandeen@redhat.com>
[ Upstream commit f4020438fab05364018c91f7e02ebdd192085933 ]
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[1] not nameval[]. Hence we need to subtract 1 from the calculation.
This can be shown by:
# touch file # setfattr -n root.a file
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@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Sasha Levin <sashal@kernel.org> --- 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 2f7e89e4be3e3..4eb2ecd31b0d2 100644 --- a/fs/xfs/libxfs/xfs_attr_leaf.c +++ b/fs/xfs/libxfs/xfs_attr_leaf.c @@ -996,8 +996,10 @@ 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. */ -- 2.25.1
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