net: Fix a data-race around sysctl_somaxconn.

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>

diff --git a/net/socket.c b/net/socket.c
index 9b27c5e4e5ba829c2fc31a74e3b38aa2c0b006a1..7378375d3a5b6d03b5deb06d7de0efbadc947182 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1801,7 +1801,7 @@ int __sys_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;