ipv4: Fix data-races around sysctl_ip_dynaddr.

[ Upstream commit e49e4aff7ec19b2d0d0957ee30e93dade57dab9e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index 8d77248..b8b6704 100644 (file)
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -1157,7 +1157,7 @@ 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 77534b4..44f2127 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1251,7 +1251,7 @@ 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);
        }
@@ -1306,7 +1306,7 @@ 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)