From: Kuniyuki Iwashima kuniyu@google.com
[ Upstream commit 893c49a78d9f85e4b8081b908fb7c407d018106a ]
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: 27069e7cb3d1 ("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 Stable-dep-of: 833d4313bc1e ("mptcp: reset blackhole on success with non-loopback ifaces") Signed-off-by: Sasha Levin sashal@kernel.org --- net/mptcp/ctrl.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index 6a97d11bda7e2..9e1f61b02a66e 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -381,12 +381,15 @@ void mptcp_active_enable(struct sock *sk) struct mptcp_pernet *pernet = mptcp_get_pernet(sock_net(sk));
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); - - dst_release(dst); + rcu_read_unlock(); } }