From: xiaohuizhang98 <[email protected]>
We detected a suspected bug with our code clone detection tool.
Similar to the handling of l2tp_tunnel_get in commit a622b40035d1
("l2ip: fix possible use-after-free"), we thought a patch might
be needed here as well.
Before taking a refcount on a rcu protected structure,
we need to make sure the refcount is not zero.
Signed-off-by: xiaohuizhang98 <[email protected]>
---
net/l2tp/l2tp_core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 7499c51b1850..b759fbd09b65 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -252,8 +252,8 @@ struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
rcu_read_lock_bh();
hlist_for_each_entry_rcu(session, session_list, hlist)
- if (session->session_id == session_id) {
- l2tp_session_inc_refcount(session);
+ if (session->session_id == session_id &&
+ refcount_inc_not_zero(&session->ref_count)) {
rcu_read_unlock_bh();
return session;
--
2.17.1