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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, Pan Bian <bianpan2016@163.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Ernesto A. Fernandez" <ernesto.mnd.fernandez@gmail.com>,
        Joe Perches <joe@perches.com>,
        Viacheslav Dubeyko <slava@dubeyko.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.4 36/88] hfsplus: do not free node before using
Date:   Fri, 14 Dec 2018 13:00:10 +0100
Message-Id: <20181214115705.130793524@linuxfoundation.org>
In-Reply-To: <20181214115702.151309521@linuxfoundation.org>
References: <20181214115702.151309521@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit c7d7d620dcbd2a1c595092280ca943f2fced7bbd ]

hfs_bmap_free() frees node via hfs_bnode_put(node).  However it then
reads node->this when dumping error message on an error path, which may
result in a use-after-free bug.  This patch frees node only when it is
never used.

Link: http://lkml.kernel.org/r/1543053441-66942-1-git-send-email-bianpan2016@163.com
Signed-off-by: Pan Bian <bianpan2016@163.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ernesto A. Fernandez <ernesto.mnd.fernandez@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Viacheslav Dubeyko <slava@dubeyko.com>
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/btree.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/hfsplus/btree.c b/fs/hfsplus/btree.c
index 3345c7553edc..7adc8a327e03 100644
--- a/fs/hfsplus/btree.c
+++ b/fs/hfsplus/btree.c
@@ -453,14 +453,15 @@ void hfs_bmap_free(struct hfs_bnode *node)
 
 		nidx -= len * 8;
 		i = node->next;
-		hfs_bnode_put(node);
 		if (!i) {
 			/* panic */;
 			pr_crit("unable to free bnode %u. "
 					"bmap not found!\n",
 				node->this);
+			hfs_bnode_put(node);
 			return;
 		}
+		hfs_bnode_put(node);
 		node = hfs_bnode_find(tree, i);
 		if (IS_ERR(node))
 			return;
-- 
2.19.1