[PATCH net-next 04/13] ipv6: annotate data-races around cnf.hop_limit

[Eric Dumazet <edumazet@google.com>]

idev->cnf.hop_limit and net->ipv6.devconf_all->hop_limit
might be read locklessly, add appropriate READ_ONCE()
and WRITE_ONCE() annotations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/ethernet/netronome/nfp/flower/action.c | 2 +-
 net/ipv6/ipv6_sockglue.c                           | 2 +-
 net/ipv6/ndisc.c                                   | 2 +-
 net/ipv6/netfilter/nf_reject_ipv6.c                | 4 ++--
 net/ipv6/output_core.c                             | 4 ++--
 net/netfilter/nf_synproxy_core.c                   | 2 +-
 6 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/flower/action.c b/drivers/net/ethernet/netronome/nfp/flower/action.c
index 2b383d92d7f573b450ed3e315af3f07de56c1921..2c3f629079584024ed9d1640a980f4894b987115 100644
--- a/drivers/net/ethernet/netronome/nfp/flower/action.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/action.c
@@ -460,7 +460,7 @@ nfp_fl_set_tun(struct nfp_app *app, struct nfp_fl_set_tun *set_tun,
 			set_tun->ttl = ip6_dst_hoplimit(dst);
 			dst_release(dst);
 		} else {
-			set_tun->ttl = net->ipv6.devconf_all->hop_limit;
+			set_tun->ttl = READ_ONCE(net->ipv6.devconf_all->hop_limit);
 		}
 #endif
 	} else {
diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c
index 56c3c467f9deb907ac6e6b84dcd33ec44bde0682..f61d977ac0528e190d901c9b5e71b1cf358096bd 100644
--- a/net/ipv6/ipv6_sockglue.c
+++ b/net/ipv6/ipv6_sockglue.c
@@ -1346,7 +1346,7 @@ int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
 		}
 
 		if (val < 0)
-			val = sock_net(sk)->ipv6.devconf_all->hop_limit;
+			val = READ_ONCE(sock_net(sk)->ipv6.devconf_all->hop_limit);
 		break;
 	}
 
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index e96d79cd34d27ca304c5f71b6db41b99d2dd8856..9c9c31268432ee58c1a381d0333d85a558a602e1 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1423,7 +1423,7 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
 	if (in6_dev->cnf.accept_ra_min_hop_limit < 256 &&
 	    ra_msg->icmph.icmp6_hop_limit) {
 		if (in6_dev->cnf.accept_ra_min_hop_limit <= ra_msg->icmph.icmp6_hop_limit) {
-			in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
+			WRITE_ONCE(in6_dev->cnf.hop_limit, ra_msg->icmph.icmp6_hop_limit);
 			fib6_metric_set(rt, RTAX_HOPLIMIT,
 					ra_msg->icmph.icmp6_hop_limit);
 		} else {
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index 196dd4ecb5e215f8a1de321bf249bec6fca6b97c..dedee264b8f6c8e5155074c6788c53fdf228ca3c 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -83,7 +83,7 @@ struct sk_buff *nf_reject_skb_v6_tcp_reset(struct net *net,
 
 	skb_reserve(nskb, LL_MAX_HEADER);
 	nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP,
-				     net->ipv6.devconf_all->hop_limit);
+				     READ_ONCE(net->ipv6.devconf_all->hop_limit));
 	nf_reject_ip6_tcphdr_put(nskb, oldskb, oth, otcplen);
 	nip6h->payload_len = htons(nskb->len - sizeof(struct ipv6hdr));
 
@@ -124,7 +124,7 @@ struct sk_buff *nf_reject_skb_v6_unreach(struct net *net,
 
 	skb_reserve(nskb, LL_MAX_HEADER);
 	nip6h = nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_ICMPV6,
-				     net->ipv6.devconf_all->hop_limit);
+				     READ_ONCE(net->ipv6.devconf_all->hop_limit));
 
 	skb_reset_transport_header(nskb);
 	icmp6h = skb_put_zero(nskb, sizeof(struct icmp6hdr));
diff --git a/net/ipv6/output_core.c b/net/ipv6/output_core.c
index b5205311f372bdaaff140d651e4b42b27a3ed805..806d4b5dd1e60b27726facbb59bbef97d6fee7f5 100644
--- a/net/ipv6/output_core.c
+++ b/net/ipv6/output_core.c
@@ -111,9 +111,9 @@ int ip6_dst_hoplimit(struct dst_entry *dst)
 		rcu_read_lock();
 		idev = __in6_dev_get(dev);
 		if (idev)
-			hoplimit = idev->cnf.hop_limit;
+			hoplimit = READ_ONCE(idev->cnf.hop_limit);
 		else
-			hoplimit = dev_net(dev)->ipv6.devconf_all->hop_limit;
+			hoplimit = READ_ONCE(dev_net(dev)->ipv6.devconf_all->hop_limit);
 		rcu_read_unlock();
 	}
 	return hoplimit;
diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c
index fbbc4fd373495b69940e29e657fde2cdc67b55db..5b140c12b7dfa40efc9bec6f2588c4350fed6bfb 100644
--- a/net/netfilter/nf_synproxy_core.c
+++ b/net/netfilter/nf_synproxy_core.c
@@ -800,7 +800,7 @@ synproxy_build_ip_ipv6(struct net *net, struct sk_buff *skb,
 	skb_reset_network_header(skb);
 	iph = skb_put(skb, sizeof(*iph));
 	ip6_flow_hdr(iph, 0, 0);
-	iph->hop_limit	= net->ipv6.devconf_all->hop_limit;
+	iph->hop_limit	= READ_ONCE(net->ipv6.devconf_all->hop_limit);
 	iph->nexthdr	= IPPROTO_TCP;
 	iph->saddr	= *saddr;
 	iph->daddr	= *daddr;
-- 
2.44.0.rc1.240.g4c46232300-goog