ipv4: Fix data-races around sysctl_ip_dynaddr.

While reading sysctl_ip_dynaddr, 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>

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 0e58001f8580368de96e5fd82c8bdcf043f4147a..b3a534ed0e7c5fa1de2f847a67c8308f8b8342cd 100644 (file)
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1179,7 +1179,7 @@ ip_autobind_reuse - BOOLEAN
        option should only be set by experts.
        Default: 0
 
-ip_dynaddr - BOOLEAN
+ip_dynaddr - INTEGER
        If set non-zero, enables support for dynamic addresses.
        If set to a non-zero value larger than 1, a kernel log
        message will be printed when dynamic address rewriting

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 93da9f783bec52e4bda6213dc78ef3820e180cc4..ac67f6b4ec700cc0a83aeb8a72a38096b4d0fc7f 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1246,7 +1246,7 @@ static int inet_sk_reselect_saddr(struct sock *sk)
        if (new_saddr == old_saddr)
                return 0;
 
-       if (sock_net(sk)->ipv4.sysctl_ip_dynaddr > 1) {
+       if (READ_ONCE(sock_net(sk)->ipv4.sysctl_ip_dynaddr) > 1) {
                pr_info("%s(): shifting inet->saddr from %pI4 to %pI4\n",
                        __func__, &old_saddr, &new_saddr);
        }
@@ -1301,7 +1301,7 @@ int inet_sk_rebuild_header(struct sock *sk)
                 * Other protocols have to map its equivalent state to TCP_SYN_SENT.
                 * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
                 */
-               if (!sock_net(sk)->ipv4.sysctl_ip_dynaddr ||
+               if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_ip_dynaddr) ||
                    sk->sk_state != TCP_SYN_SENT ||
                    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
                    (err = inet_sk_reselect_saddr(sk)) != 0)