6.12-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 9b8c88f875c04d4cb9111bd5dd9291c7e9691bf5 ]
pppol2tp_session_get_sock() is using RCU, it must be ready for sk_refcnt being zero.
Commit ee40fb2e1eb5 ("l2tp: protect sock pointer of struct pppol2tp_session with RCU") was correct because it had a call_rcu(..., pppol2tp_put_sk) which was later removed in blamed commit.
pppol2tp_recv() can use pppol2tp_session_get_sock() as well.
Fixes: c5cbaef992d6 ("l2tp: refactor ppp socket/session relationship") Signed-off-by: Eric Dumazet edumazet@google.com Cc: James Chapman jchapman@katalix.com Reviewed-by: Guillaume Nault gnault@redhat.com Link: https://patch.msgid.link/20250826134435.1683435-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/l2tp/l2tp_ppp.c | 25 ++++++++----------------- 1 file changed, 8 insertions(+), 17 deletions(-)
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index 53baf2dd5d5da..16c514f628eac 100644 --- a/net/l2tp/l2tp_ppp.c +++ b/net/l2tp/l2tp_ppp.c @@ -129,22 +129,12 @@ static const struct ppp_channel_ops pppol2tp_chan_ops = {
static const struct proto_ops pppol2tp_ops;
-/* Retrieves the pppol2tp socket associated to a session. - * A reference is held on the returned socket, so this function must be paired - * with sock_put(). - */ +/* Retrieves the pppol2tp socket associated to a session. */ static struct sock *pppol2tp_session_get_sock(struct l2tp_session *session) { struct pppol2tp_session *ps = l2tp_session_priv(session); - struct sock *sk; - - rcu_read_lock(); - sk = rcu_dereference(ps->sk); - if (sk) - sock_hold(sk); - rcu_read_unlock();
- return sk; + return rcu_dereference(ps->sk); }
/* Helpers to obtain tunnel/session contexts from sockets. @@ -206,14 +196,13 @@ static int pppol2tp_recvmsg(struct socket *sock, struct msghdr *msg,
static void pppol2tp_recv(struct l2tp_session *session, struct sk_buff *skb, int data_len) { - struct pppol2tp_session *ps = l2tp_session_priv(session); - struct sock *sk = NULL; + struct sock *sk;
/* If the socket is bound, send it in to PPP's input queue. Otherwise * queue it on the session socket. */ rcu_read_lock(); - sk = rcu_dereference(ps->sk); + sk = pppol2tp_session_get_sock(session); if (!sk) goto no_sock;
@@ -510,13 +499,14 @@ static void pppol2tp_show(struct seq_file *m, void *arg) struct l2tp_session *session = arg; struct sock *sk;
+ rcu_read_lock(); sk = pppol2tp_session_get_sock(session); if (sk) { struct pppox_sock *po = pppox_sk(sk);
seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan)); - sock_put(sk); } + rcu_read_unlock(); }
static void pppol2tp_session_init(struct l2tp_session *session) @@ -1529,6 +1519,7 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v) port = ntohs(inet->inet_sport); }
+ rcu_read_lock(); sk = pppol2tp_session_get_sock(session); if (sk) { state = sk->sk_state; @@ -1564,8 +1555,8 @@ static void pppol2tp_seq_session_show(struct seq_file *m, void *v) struct pppox_sock *po = pppox_sk(sk);
seq_printf(m, " interface %s\n", ppp_dev_name(&po->chan)); - sock_put(sk); } + rcu_read_unlock(); }
static int pppol2tp_seq_show(struct seq_file *m, void *v)