ip: Fix data-races around sysctl_ip_no_pmtu_disc.

While reading sysctl_ip_no_pmtu_disc, 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/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index ac67f6b..4bc24f9 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -335,7 +335,7 @@ lookup_protocol:
                        inet->hdrincl = 1;
        }
 
-       if (net->ipv4.sysctl_ip_no_pmtu_disc)
+       if (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc))
                inet->pmtudisc = IP_PMTUDISC_DONT;
        else
                inet->pmtudisc = IP_PMTUDISC_WANT;

diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 57c4f0d..d5d745c 100644 (file)
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -881,7 +881,7 @@ static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
                         * values please see
                         * Documentation/networking/ip-sysctl.rst
                         */
-                       switch (net->ipv4.sysctl_ip_no_pmtu_disc) {
+                       switch (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc)) {
                        default:
                                net_dbg_ratelimited("%pI4: fragmentation needed and DF set\n",
                                                    &iph->daddr);

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 70564dd..6f354f8 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -226,7 +226,7 @@ lookup_protocol:
        RCU_INIT_POINTER(inet->mc_list, NULL);
        inet->rcv_tos   = 0;
 
-       if (net->ipv4.sysctl_ip_no_pmtu_disc)
+       if (READ_ONCE(net->ipv4.sysctl_ip_no_pmtu_disc))
                inet->pmtudisc = IP_PMTUDISC_DONT;
        else
                inet->pmtudisc = IP_PMTUDISC_WANT;

diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 08564e0..ccfb172 100644 (file)
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -2620,7 +2620,7 @@ int __xfrm_init_state(struct xfrm_state *x, bool init_replay, bool offload)
        int err;
 
        if (family == AF_INET &&
-           xs_net(x)->ipv4.sysctl_ip_no_pmtu_disc)
+           READ_ONCE(xs_net(x)->ipv4.sysctl_ip_no_pmtu_disc))
                x->props.flags |= XFRM_STATE_NOPMTUDISC;
 
        err = -EPROTONOSUPPORT;