From: Jason Xing <kernelxing@tencent.com>
Date: Fri, 8 Mar 2024 11:25:03 +0000 (+0800)
Subject: mptcp: annotate a data-race around sysctl_tcp_wmem[0]
X-Git-Tag: v6.9-rc1~159^2~29^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9eb430d40e449640122b0b33ace1f33e793ecc5f;p=thirdparty%2Fkernel%2Flinux.git

mptcp: annotate a data-race around sysctl_tcp_wmem[0]

It's possible that writer and the reader can manipulate the same
sysctl knob concurrently. Using READ_ONCE() to prevent reading
an old value.

Signed-off-by: Jason Xing <kernelxing@tencent.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index f16edef6026a3..a10ebf3ee10a1 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -850,7 +850,7 @@ static inline void __mptcp_sync_sndbuf(struct sock *sk)
 	if (sk->sk_userlocks & SOCK_SNDBUF_LOCK)
 		return;
 
-	new_sndbuf = sock_net(sk)->ipv4.sysctl_tcp_wmem[0];
+	new_sndbuf = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[0]);
 	mptcp_for_each_subflow(mptcp_sk(sk), subflow) {
 		ssk_sndbuf =  READ_ONCE(mptcp_subflow_tcp_sock(subflow)->sk_sndbuf);