mptcp: Use __sk_dst_get() and dst_dev_rcu() in mptcp_active_enable().

mptcp_active_enable() is called from subflow_finish_connect(),
which is icsk->icsk_af_ops->sk_rx_dst_set() and it's not always
under RCU.

Using sk_dst_get(sk)->dev could trigger UAF.

Let's use __sk_dst_get() and dst_dev_rcu().

Fixes: 27069e7cb3 ("mptcp: disable active MPTCP in case of blackhole")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250916214758.650211-8-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2025-09-16 21:47:25 +00:00 committed by Jakub Kicinski
parent 108a86c71c
commit 893c49a78d

View file

@ -501,12 +501,15 @@ void mptcp_active_enable(struct sock *sk)
struct mptcp_pernet *pernet = mptcp_get_pernet(sock_net(sk)); struct mptcp_pernet *pernet = mptcp_get_pernet(sock_net(sk));
if (atomic_read(&pernet->active_disable_times)) { if (atomic_read(&pernet->active_disable_times)) {
struct dst_entry *dst = sk_dst_get(sk); struct net_device *dev;
struct dst_entry *dst;
if (dst && dst->dev && (dst->dev->flags & IFF_LOOPBACK)) rcu_read_lock();
dst = __sk_dst_get(sk);
dev = dst ? dst_dev_rcu(dst) : NULL;
if (dev && (dev->flags & IFF_LOOPBACK))
atomic_set(&pernet->active_disable_times, 0); atomic_set(&pernet->active_disable_times, 0);
rcu_read_unlock();
dst_release(dst);
} }
} }