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 c74cfe1ee1699663329d5b1f54a4663dfcbd3c76..7bcd7053e61f2b639e6ee0f96dc53a5f15d9c916 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1509,7 +1509,7 @@ 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;