nexthop: Fix data-races around nexthop_compat_mode.

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

Fixes: c42c4d1c4809 ("net: ipv4: add sysctl for nexthop api compatibility mode")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index a57ba23571c96eb218939294b0077cdc5fe158f9..16dbd5075284b24f975dbb418d9af54f87dfbd96 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1811,7 +1811,7 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
                        goto nla_put_failure;
                if (nexthop_is_blackhole(fi->nh))
                        rtm->rtm_type = RTN_BLACKHOLE;
-               if (!fi->fib_net->ipv4.sysctl_nexthop_compat_mode)
+               if (!READ_ONCE(fi->fib_net->ipv4.sysctl_nexthop_compat_mode))
                        goto offload;
        }
 

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index e459a391e607d34e16828bef13a5ce22ba6dde89..853a75a8fbafc94806aa3984b5091baed7d805a5 100644 (file)
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1858,7 +1858,7 @@ static void __remove_nexthop_fib(struct net *net, struct nexthop *nh)
                /* __ip6_del_rt does a release, so do a hold here */
                fib6_info_hold(f6i);
                ipv6_stub->ip6_del_rt(net, f6i,
-                                     !net->ipv4.sysctl_nexthop_compat_mode);
+                                     !READ_ONCE(net->ipv4.sysctl_nexthop_compat_mode));
        }
 }
 
@@ -2361,7 +2361,8 @@ out:
        if (!rc) {
                nh_base_seq_inc(net);
                nexthop_notify(RTM_NEWNEXTHOP, new_nh, &cfg->nlinfo);
-               if (replace_notify && net->ipv4.sysctl_nexthop_compat_mode)
+               if (replace_notify &&
+                   READ_ONCE(net->ipv4.sysctl_nexthop_compat_mode))
                        nexthop_replace_notify(net, new_nh, &cfg->nlinfo);
        }
 

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 828355710c57b6ea588c0a58de7e9ea119c70833..916417944ec8153919533bcfc034f2bb4b6d0180 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5741,7 +5741,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
                if (nexthop_is_blackhole(rt->nh))
                        rtm->rtm_type = RTN_BLACKHOLE;
 
-               if (net->ipv4.sysctl_nexthop_compat_mode &&
+               if (READ_ONCE(net->ipv4.sysctl_nexthop_compat_mode) &&
                    rt6_fill_node_nexthop(skb, rt->nh, &nh_flags) < 0)
                        goto nla_put_failure;