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>
This commit is contained in:
Darrick J. Wong 2016-08-26 15:58:40 +10:00 committed by Dave Chinner
parent 32438cf9d5
commit ed150e1a5c

View File

@ -1814,6 +1814,10 @@ xfs_btree_lookup(
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;