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[net,4/5] mptcp: fix setsockopt(IP_TOS) subflow locking

Message ID 20231114-upstream-net-20231113-mptcp-misc-fixes-6-7-rc2-v1-4-7b9cd6a7b7f4@kernel.org
State New
Headers show
Series mptcp: misc. fixes for v6.7 | expand

Commit Message

Matthieu Baerts (NGI0) Nov. 13, 2023, 11:16 p.m. UTC 
From: Paolo Abeni <pabeni@redhat.com>

The MPTCP implementation of the IP_TOS socket option uses the lockless
variant of the TOS manipulation helper and does not hold such lock at
the helper invocation time.

Add the required locking.

Fixes: ffcacff87cd6 ("mptcp: Support for IP_TOS for MPTCP setsockopt()")
Cc: stable@vger.kernel.org
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/457
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
---
 net/mptcp/sockopt.c | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c
index 77f5e8932abf..353680733700 100644
--- a/net/mptcp/sockopt.c
+++ b/net/mptcp/sockopt.c
@@ -738,8 +738,11 @@  static int mptcp_setsockopt_v4_set_tos(struct mptcp_sock *msk, int optname,
 	val = READ_ONCE(inet_sk(sk)->tos);
 	mptcp_for_each_subflow(msk, subflow) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
+		bool slow;
 
+		slow = lock_sock_fast(ssk);
 		__ip_sock_set_tos(ssk, val);
+		unlock_sock_fast(ssk, slow);
 	}
 	release_sock(sk);