xfs: fix btree scrub checking with regards to root-in-inode

In xchk_btree_check_owner, we can be passed a null buffer pointer.  This
should only happen for the root of a root-in-inode btree type, but we
should program defensively in case the btree cursor state ever gets
screwed up and we get a null buffer anyway.

Coverity-id: 1438713
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index 6f94d1f..117910d 100644 (file)
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -415,8 +415,17 @@ xchk_btree_check_owner(
        struct xfs_btree_cur    *cur = bs->cur;
        struct check_owner      *co;
 
-       if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) && bp == NULL)
+       /*
+        * In theory, xfs_btree_get_block should only give us a null buffer
+        * pointer for the root of a root-in-inode btree type, but we need
+        * to check defensively here in case the cursor state is also screwed
+        * up.
+        */
+       if (bp == NULL) {
+               if (!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE))
+                       xchk_btree_set_corrupt(bs->sc, bs->cur, level);
                return 0;
+       }
 
        /*
         * We want to cross-reference each btree block with the bnobt