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[net,2/6] mptcp: fix locking for setsockopt corner-case

Message ID 20230207-upstream-net-20230207-various-fix-6-2-v1-2-2031b495c7cc@tessares.net (mailing list archive)
State Accepted
Commit 21e43569685de4ad773fb060c11a15f3fd5e7ac4
Headers show
Series mptcp: fixes for v6.2 | expand

Commit Message

Matthieu Baerts Feb. 7, 2023, 1:04 p.m. UTC
From: Paolo Abeni <pabeni@redhat.com>

We need to call the __mptcp_nmpc_socket(), and later subflow socket
access under the msk socket lock, or e.g. a racing connect() could
change the socket status under the hood, with unexpected results.

Fixes: 54635bd04701 ("mptcp: add TCP_FASTOPEN_CONNECT socket option")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
 net/mptcp/sockopt.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
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diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index d4b1e6ec1b36..7f2c3727ab23 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -760,14 +760,21 @@  static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 static int mptcp_setsockopt_first_sf_only(struct mptcp_sock *msk, int level, int optname,
 					  sockptr_t optval, unsigned int optlen)
+	struct sock *sk = (struct sock *)msk;
 	struct socket *sock;
+	int ret = -EINVAL;
 	/* Limit to first subflow, before the connection establishment */
+	lock_sock(sk);
 	sock = __mptcp_nmpc_socket(msk);
 	if (!sock)
-		return -EINVAL;
+		goto unlock;
-	return tcp_setsockopt(sock->sk, level, optname, optval, optlen);
+	ret = tcp_setsockopt(sock->sk, level, optname, optval, optlen);
+	release_sock(sk);
+	return ret;
 static int mptcp_setsockopt_sol_tcp(struct mptcp_sock *msk, int optname,