Messages in this thread Patch in this message | | | From | Xiaohui Zhang <> | Subject | [PATCH 1/1] l2tp: fix possible use-after-free | Date | Fri, 10 Jun 2022 13:16:33 +0800 |
| |
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: Xiaohui Zhang <xiaohuizhang@ruc.edu.cn> --- net/l2tp/l2tp_core.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c index 7499c51b1850..96e8966f900d 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; @@ -273,8 +273,8 @@ struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) rcu_read_lock_bh(); hlist_for_each_entry_rcu(session, session_list, global_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; @@ -294,8 +294,8 @@ struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) rcu_read_lock_bh(); for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { - if (++count > nth) { - l2tp_session_inc_refcount(session); + if (++count > nth && + refcount_inc_not_zero(&session->ref_count)) { rcu_read_unlock_bh(); return session; } @@ -321,8 +321,8 @@ struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, rcu_read_lock_bh(); for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { - if (!strcmp(session->ifname, ifname)) { - l2tp_session_inc_refcount(session); + if (!strcmp(session->ifname, ifname) && + refcount_inc_not_zero(&session->ref_count)) { rcu_read_unlock_bh(); return session; -- 2.17.1
| |