From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Tue, 23 Aug 2022 17:47:00 +0000 (-0700)
Subject: net: Fix a data-race around sysctl_somaxconn.
X-Git-Tag: v4.9.327~21
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=29e01227e3fcbb82443c04060fc37e7831a7774c;p=thirdparty%2Fkernel%2Fstable.git

net: Fix a data-race around sysctl_somaxconn.

[ Upstream commit 3c9ba81d72047f2e81bb535d42856517b613aba7 ]

While reading sysctl_somaxconn, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/net/socket.c b/net/socket.c
index ab64ae80ca2cd..6f1abcba0e360 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1403,7 +1403,7 @@ SYSCALL_DEFINE2(listen, int, fd, int, backlog)
 
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
 	if (sock) {
-		somaxconn = sock_net(sock->sk)->core.sysctl_somaxconn;
+		somaxconn = READ_ONCE(sock_net(sock->sk)->core.sysctl_somaxconn);
 		if ((unsigned int)backlog > somaxconn)
 			backlog = somaxconn;