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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-xfs@vger.kernel.org, xfs@oss.sgi.com
Subject: [PATCH] xfs: don't perform lookups on zero-height btrees
Date: Fri, 19 Aug 2016 13:30:22 -0700	[thread overview]
Message-ID: <20160819203022.GD8268@birch.djwong.org> (raw)

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(+)

diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 64fd847..4bffea4 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;
 

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             reply	other threads:[~2016-08-19 20:30 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-19 20:30 Darrick J. Wong [this message]
2016-08-24 18:01 ` [PATCH] xfs: don't perform lookups on zero-height btrees Brian Foster
2016-08-24 20:39   ` Darrick J. Wong
2016-08-25  8:04 ` Christoph Hellwig

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