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[2/5] xfs: don't perform lookups on zero-height btrees

Message ID 147200524120.14738.16686498030898663475.stgit@birch.djwong.org (mailing list archive)
State Accepted
Headers show

Commit Message

Darrick J. Wong Aug. 24, 2016, 2:20 a.m. UTC 
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>
---
 fs/xfs/libxfs/xfs_btree.c |    4 ++++
 1 file changed, 4 insertions(+)

Comments

Christoph Hellwig Aug. 25, 2016, 8:10 a.m. UTC | #1 
Looks fine, but could probably use an unlikely():

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox

Patch

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_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;