diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-08-26 13:44:35 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-09-04 16:55:43 +0200 |
| commit | 069eb65689974728da1c69e729c441f410c1c4a9 (patch) | |
| tree | 7ad9cdfec698ee56b6ecc366959411a7bb72ea61 | |
| parent | f6c2cc99fc2387ba6499facd6108f6543382792d (diff) | |
l2tp: do not use sock_hold() in pppol2tp_session_get_sock()
[ 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>
| -rw-r--r-- | net/l2tp/l2tp_ppp.c | 25 |
1 files changed, 8 insertions, 17 deletions
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c index fc5c2fd8f34c..5e12e7ce17d8 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 @@ end: 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) @@ -1530,6 +1520,7 @@ 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; @@ -1565,8 +1556,8 @@ 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) |