[PATCH 5.4 CANDIDATE 07/26] xfs: check owner of dir3 data blocks

[Chandan Babu R <chandan.babu@oracle.com>]

From: "Darrick J. Wong" <darrick.wong@oracle.com>

commit a10c21ed5d5241d11cf1d5a4556730840572900b upstream.

[Slightly edit xfs_dir3_data_read() to work with existing mapped_bno argument instead
of flag values introduced in later kernels]

Check the owner field of dir3 data block headers.  If it's corrupt,
release the buffer and return EFSCORRUPTED.  All callers handle this
properly.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
---
 fs/xfs/libxfs/xfs_dir2_data.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 2c79be4c3153..2d92bcd8c801 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -348,6 +348,22 @@ static const struct xfs_buf_ops xfs_dir3_data_reada_buf_ops = {
 	.verify_write = xfs_dir3_data_write_verify,
 };
 
+static xfs_failaddr_t
+xfs_dir3_data_header_check(
+	struct xfs_inode	*dp,
+	struct xfs_buf		*bp)
+{
+	struct xfs_mount	*mp = dp->i_mount;
+
+	if (xfs_sb_version_hascrc(&mp->m_sb)) {
+		struct xfs_dir3_data_hdr *hdr3 = bp->b_addr;
+
+		if (be64_to_cpu(hdr3->hdr.owner) != dp->i_ino)
+			return __this_address;
+	}
+
+	return NULL;
+}
 
 int
 xfs_dir3_data_read(
@@ -357,12 +373,24 @@ xfs_dir3_data_read(
 	xfs_daddr_t		mapped_bno,
 	struct xfs_buf		**bpp)
 {
+	xfs_failaddr_t		fa;
 	int			err;
 
 	err = xfs_da_read_buf(tp, dp, bno, mapped_bno, bpp,
 				XFS_DATA_FORK, &xfs_dir3_data_buf_ops);
-	if (!err && tp && *bpp)
-		xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_DATA_BUF);
+	if (err || !*bpp)
+		return err;
+
+	/* Check things that we can't do in the verifier. */
+	fa = xfs_dir3_data_header_check(dp, *bpp);
+	if (fa) {
+		__xfs_buf_mark_corrupt(*bpp, fa);
+		xfs_trans_brelse(tp, *bpp);
+		*bpp = NULL;
+		return -EFSCORRUPTED;
+	}
+
+	xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_DATA_BUF);
 	return err;
 }
 
-- 
2.35.1