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From cb7ccb9924bb3596f211badf0d2becf131a979cd Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Tue, 17 Apr 2018 19:10:15 -0700
Subject: [PATCH] xfs: don't fail when converting shortform attr to long form
 during ATTR_REPLACE

commit 7b38460dc8e4eafba06c78f8e37099d3b34d473c upstream.

Kanda Motohiro reported that expanding a tiny xattr into a large xattr
fails on XFS because we remove the tiny xattr from a shortform fork and
then try to re-add it after converting the fork to extents format having
not removed the ATTR_REPLACE flag.  This fails because the attr is no
longer present, causing a fs shutdown.

This is derived from the patch in his bug report, but we really
shouldn't ignore a nonzero retval from the remove call.

CVE: CVE-2018-18690
Upstream-Status: Backport

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199119
Reported-by: kanda.motohiro@gmail.com
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
---
 fs/xfs/libxfs/xfs_attr.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
index 6249c92671de..ea66f04f46f7 100644
--- a/fs/xfs/libxfs/xfs_attr.c
+++ b/fs/xfs/libxfs/xfs_attr.c
@@ -501,7 +501,14 @@ xfs_attr_shortform_addname(xfs_da_args_t *args)
 		if (args->flags & ATTR_CREATE)
 			return retval;
 		retval = xfs_attr_shortform_remove(args);
-		ASSERT(retval == 0);
+		if (retval)
+			return retval;
+		/*
+		 * Since we have removed the old attr, clear ATTR_REPLACE so
+		 * that the leaf format add routine won't trip over the attr
+		 * not being around.
+		 */
+		args->flags &= ~ATTR_REPLACE;
 	}
 
 	if (args->namelen >= XFS_ATTR_SF_ENTSIZE_MAX ||
-- 
2.19.2