nexthop: Fix data-races around nexthop_compat_mode.

[ Upstream commit bdf00bf24bef9be1ca641a6390fd5487873e0d2e ]

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

Fixes: 4f80116d3df3 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index a98350d..674694d 100644 (file)
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1829,7 +1829,7 @@ 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 5dbd4b5..cc8f120 100644 (file)
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -1857,7 +1857,7 @@ 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));
        }
 }
 
@@ -2362,7 +2362,8 @@ 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 4ca754c..27274fc 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5756,7 +5756,7 @@ 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;