xfs: don't perform lookups on zero-height btrees
If the caller passes in a cursor to a zero-height btree (which is
impossible), we never set block to anything but NULL, which causes the
later dereference of it to crash. Instead, just return -EFSCORRUPTED.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
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 b5c213a..33f1406 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -1814,6 +1814,10 @@
XFS_BTREE_STATS_INC(cur, lookup);
+ /* No such thing as a zero-level tree. */
+ if (cur->bc_nlevels == 0)
+ return -EFSCORRUPTED;
+
block = NULL;
keyno = 0;