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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "=?UTF-8?q?Ernesto=20A . =20Fern=C3=A1ndez?=" 
        <ernesto.mnd.fernandez@gmail.com>,
        Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 071/151] hfsplus: fix BUG on bnode parent update
Date:   Wed, 27 Nov 2019 21:30:54 +0100
Message-Id: <20191127203034.579519020@linuxfoundation.org>
In-Reply-To: <20191127203000.773542911@linuxfoundation.org>
References: <20191127203000.773542911@linuxfoundation.org>
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From: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>

[ Upstream commit 19a9d0f1acf75e8be8cfba19c1a34e941846fa2b ]

Creating, renaming or deleting a file may hit BUG_ON() if the first
record of both a leaf node and its parent are changed, and if this
forces the parent to be split.  This bug is triggered by xfstests
generic/027, somewhat rarely; here is a more reliable reproducer:

  truncate -s 50M fs.iso
  mkfs.hfsplus fs.iso
  mount fs.iso /mnt
  i=1000
  while [ $i -le 2400 ]; do
    touch /mnt/$i &>/dev/null
    ((++i))
  done
  i=2400
  while [ $i -ge 1000 ]; do
    mv /mnt/$i /mnt/$(perl -e "print $i x61") &>/dev/null
    ((--i))
  done

The issue is that a newly created bnode is being put twice.  Reset
new_node to NULL in hfs_brec_update_parent() before reaching goto again.

Link: http://lkml.kernel.org/r/5ee1db09b60373a15890f6a7c835d00e76bf601d.1535682461.git.ernesto.mnd.fernandez@gmail.com
Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/hfsplus/brec.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
index 1002a0c08319b..20ce698251ad1 100644
--- a/fs/hfsplus/brec.c
+++ b/fs/hfsplus/brec.c
@@ -447,6 +447,7 @@ static int hfs_brec_update_parent(struct hfs_find_data *fd)
 			/* restore search_key */
 			hfs_bnode_read_key(node, fd->search_key, 14);
 		}
+		new_node = NULL;
 	}
 
 	if (!rec && node->parent)
-- 
2.20.1