From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Tue, 12 Jul 2022 00:15:33 +0000 (-0700)
Subject: nexthop: Fix data-races around nexthop_compat_mode.
X-Git-Tag: v5.10.132~50
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=a51040d4b120f3520df64fb0b9c63b31d69bea9b;p=users%2Fdwmw2%2Flinux.git

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 845adb92ef706..70c866308abea 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1831,7 +1831,7 @@ 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 8bd3f5e3c0e7a..2a17dc9413ae9 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -882,7 +882,7 @@ 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));
 	}
 }
 
@@ -1194,7 +1194,8 @@ 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 e67505c6d8562..cdf215442d373 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -5641,7 +5641,7 @@ 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;