[PATCH 4.4 35/88] hfs: do not free node before using

From: Greg Kroah-Hartman
Date: Fri Dec 14 2018 - 07:20:07 EST

4.4-stable review patch. If anyone has any objections, please let me know.


[ Upstream commit ce96a407adef126870b3f4a1b73529dd8aa80f49 ]

hfs_bmap_free() frees the 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 the node only when
it is never again used.

Link: http://lkml.kernel.org/r/1542963889-128825-1-git-send-email-bianpan2016@xxxxxxx
Fixes: a1185ffa2fc ("HFS rewrite")
Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Ernesto A. Fernandez <ernesto.mnd.fernandez@xxxxxxxxx>
Cc: Viacheslav Dubeyko <slava@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
fs/hfs/btree.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c
index 1ab19e660e69..1ff5774a5382 100644
--- a/fs/hfs/btree.c
+++ b/fs/hfs/btree.c
@@ -328,13 +328,14 @@ 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",
+ hfs_bnode_put(node);
+ hfs_bnode_put(node);
node = hfs_bnode_find(tree, i);
if (IS_ERR(node))