tcp: Fix data-races around sysctl_tcp_moderate_rcvbuf.

commit 780476488844e070580bfc9e3bc7832ec1cea883 upstream.

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

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index b9fd518..426f8fe 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -716,7 +716,7 @@ void tcp_rcv_space_adjust(struct sock *sk)
         * <prev RTT . ><current RTT .. ><next RTT .... >
         */
 
-       if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
+       if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
            !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
                int rcvmem, rcvbuf;
                u64 rcvwin, grow;

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index d6def23..01ede89 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -1881,7 +1881,7 @@ static void mptcp_rcv_space_adjust(struct mptcp_sock *msk, int copied)
        if (msk->rcvq_space.copied <= msk->rcvq_space.space)
                goto new_measure;
 
-       if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
+       if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf) &&
            !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
                int rcvmem, rcvbuf;
                u64 rcvwin, grow;