From: Dave Chinner <dchinner@redhat.com>
Date: Wed, 22 Jun 2022 19:28:52 +0000 (-0500)
Subject: xfs: detect empty attr leaf blocks in xfs_attr3_leaf_verify
X-Git-Tag: v5.19.0-rc0~26
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d45dd440f5ef2229ab3c671870e993a342415d5b;p=thirdparty%2Fxfsprogs-dev.git

xfs: detect empty attr leaf blocks in xfs_attr3_leaf_verify

Source kernel commit: 51e6104fdb95f377c8741794778319bd413f4fff

xfs_repair flags these as a corruption error, so the verifier should
catch software bugs that result in empty leaf blocks being written
to disk, too.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
---

diff --git a/libxfs/xfs_attr_leaf.c b/libxfs/xfs_attr_leaf.c
index 04f34d0ee..75b8f08ed 100644
--- a/libxfs/xfs_attr_leaf.c
+++ b/libxfs/xfs_attr_leaf.c
@@ -307,6 +307,15 @@ xfs_attr3_leaf_verify(
 	if (fa)
 		return fa;
 
+	/*
+	 * Empty leaf blocks should never occur;  they imply the existence of a
+	 * software bug that needs fixing. xfs_repair also flags them as a
+	 * corruption that needs fixing, so we should never let these go to
+	 * disk.
+	 */
+	if (ichdr.count == 0)
+		return __this_address;
+
 	/*
 	 * firstused is the block offset of the first name info structure.
 	 * Make sure it doesn't go off the block or crash into the header.