Messages in this thread Patch in this message | | | From | Xiaohui Zhang <> | Subject | [PATCH 1/1] l2tp: fix possible use-after-free | Date | Sun, 5 Jun 2022 19:35:03 +0800 |
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From: xiaohuizhang98 <ruc_zhangxiaohui@163.com>
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 <ruc_zhangxiaohui@163.com> --- 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
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