netdev - [PATCH v2 net-next 11/15] ipv6: annotate data-races around devconf->disable

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Date: Tue, 27 Feb 2024 15:01:56 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, Jiri Pirko <jiri@...dia.com>, netdev@...r.kernel.org, 
	eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH v2 net-next 11/15] ipv6: annotate data-races around devconf->disable_policy

idev->cnf.disable_policy and net->ipv6.devconf_all->disable_policy
can be read locklessly. Add appropriate annotations on reads
and writes.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/ipv6/addrconf.c   | 2 +-
 net/ipv6/ip6_output.c | 4 ++--
 net/ipv6/route.c      | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 8637957ab9c8fcfce2a81910c8ae0e965f32b7f4..392e64df991a4005736883af128cd82ac3895167 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -6697,7 +6697,7 @@ int addrconf_disable_policy(struct ctl_table *ctl, int *valp, int val)
 	if (!rtnl_trylock())
 		return restart_syscall();
 
-	*valp = val;
+	WRITE_ONCE(*valp, val);
 
 	net = (struct net *)ctl->extra2;
 	if (valp == &net->ipv6.devconf_dflt->disable_policy) {
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index f08af3f4e54f5dcb0b8b5fb8f60463e41bd1f578..b9dd3a66e4236fbf67af75c5f98c921b38c18bf6 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -513,8 +513,8 @@ int ip6_forward(struct sk_buff *skb)
 	if (skb_warn_if_lro(skb))
 		goto drop;
 
-	if (!net->ipv6.devconf_all->disable_policy &&
-	    (!idev || !idev->cnf.disable_policy) &&
+	if (!READ_ONCE(net->ipv6.devconf_all->disable_policy) &&
+	    (!idev || !READ_ONCE(idev->cnf.disable_policy)) &&
 	    !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
 		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 		goto drop;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1b897c57c55fe22eff71a22b51ad25269db622f5..a92fcac902aea9307e0c83d150e9d1c41435887f 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4584,8 +4584,8 @@ struct fib6_info *addrconf_f6i_alloc(struct net *net,
 		f6i->dst_nocount = true;
 
 		if (!anycast &&
-		    (net->ipv6.devconf_all->disable_policy ||
-		     idev->cnf.disable_policy))
+		    (READ_ONCE(net->ipv6.devconf_all->disable_policy) ||
+		     READ_ONCE(idev->cnf.disable_policy)))
 			f6i->dst_nopolicy = true;
 	}
 
-- 
2.44.0.rc1.240.g4c46232300-goog