xfs: check for bogus values in btree block headers

When we're reading a btree block, make sure that what we retrieved
matches the owner and level; and has a plausible number of records.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 0e80993c8a5914d3dfa1f861b2b459d7a513d67a..21e6a6ab6b9a4001f25313fd32bab0b79ec11ae4 100644 (file)
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -1769,8 +1769,28 @@ xfs_btree_lookup_get_block(
        if (error)
                return error;
 
+       /* Check the inode owner since the verifiers don't. */
+       if (xfs_sb_version_hascrc(&cur->bc_mp->m_sb) &&
+           (cur->bc_flags & XFS_BTREE_LONG_PTRS) &&
+           be64_to_cpu((*blkp)->bb_u.l.bb_owner) !=
+                       cur->bc_private.b.ip->i_ino)
+               goto out_bad;
+
+       /* Did we get the level we were looking for? */
+       if (be16_to_cpu((*blkp)->bb_level) != level)
+               goto out_bad;
+
+       /* Check that internal nodes have at least one record. */
+       if (level != 0 && be16_to_cpu((*blkp)->bb_numrecs) == 0)
+               goto out_bad;
+
        xfs_btree_setbuf(cur, level, bp);
        return 0;
+
+out_bad:
+       *blkp = NULL;
+       xfs_trans_brelse(cur->bc_tp, bp);
+       return -EFSCORRUPTED;
 }
 
 /*