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

Darrick J. Wong
2019-03-18T16:43:40Z

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

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>
---
fs/xfs/scrub/btree.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
index 6271a277eabe..cf4046c9e250 100644
--- a/fs/xfs/scrub/btree.c
+++ b/fs/xfs/scrub/btree.c
@@ -481,8 +481,17 @@ 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