[PATCH AUTOSEL 5.10 18/65] ipv6: make mc_forwarding atomic - B.A.T.M.A.N - lists.open-mesh.org

1 Apr 2022

From: Eric Dumazet edumazet@google.com
[ Upstream commit 145c7a793838add5e004e7d49a67654dc7eba147 ]
This fixes minor data-races in ip6_mc_input() and
batadv_mcast_mla_rtr_flags_softif_get_ipv6()
Signed-off-by: Eric Dumazet edumazet@google.com
Signed-off-by: David S. Miller davem@davemloft.net
Signed-off-by: Sasha Levin sashal@kernel.org
---
 include/linux/ipv6.h       | 2 +-
 net/batman-adv/multicast.c | 2 +-
 net/ipv6/addrconf.c        | 4 ++--
 net/ipv6/ip6_input.c       | 2 +-
 net/ipv6/ip6mr.c           | 8 ++++----
 5 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index f514a7dd8c9c..510f87656479 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -50,7 +50,7 @@ struct ipv6_devconf {
    __s32		use_optimistic;
 #endif
 #ifdef CONFIG_IPV6_MROUTE
-	__s32		mc_forwarding;
+	atomic_t	mc_forwarding;
 #endif
    __s32		disable_ipv6;
    __s32		drop_unicast_in_l2_multicast;
diff --git a/net/batman-adv/multicast.c b/net/batman-adv/multicast.c
index 139894ca788b..c8a341cd652c 100644
--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -136,7 +136,7 @@ static u8 batadv_mcast_mla_rtr_flags_softif_get_ipv6(struct net_device *dev)
 {
    struct inet6_dev *in6_dev = __in6_dev_get(dev);
-	if (in6_dev && in6_dev->cnf.mc_forwarding)
+	if (in6_dev && atomic_read(&in6_dev->cnf.mc_forwarding))
    	return BATADV_NO_FLAGS;
    else
    	return BATADV_MCAST_WANT_NO_RTR6;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 7c5bf39dca5d..86bcb1825698 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -542,7 +542,7 @@ static int inet6_netconf_fill_devconf(struct sk_buff *skb, int ifindex,
 #ifdef CONFIG_IPV6_MROUTE
    if ((all || type == NETCONFA_MC_FORWARDING) &&
        nla_put_s32(skb, NETCONFA_MC_FORWARDING,
-			devconf->mc_forwarding) < 0)
+			atomic_read(&devconf->mc_forwarding)) < 0)
    	goto nla_put_failure;
 #endif
    if ((all || type == NETCONFA_PROXY_NEIGH) &&
@@ -5515,7 +5515,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf,
    array[DEVCONF_USE_OPTIMISTIC] = cnf->use_optimistic;
 #endif
 #ifdef CONFIG_IPV6_MROUTE
-	array[DEVCONF_MC_FORWARDING] = cnf->mc_forwarding;
+	array[DEVCONF_MC_FORWARDING] = atomic_read(&cnf->mc_forwarding);
 #endif
    array[DEVCONF_DISABLE_IPV6] = cnf->disable_ipv6;
    array[DEVCONF_ACCEPT_DAD] = cnf->accept_dad;
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 06d60662717d..15ea3d082534 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -509,7 +509,7 @@ int ip6_mc_input(struct sk_buff *skb)
    /*
     *      IPv6 multicast router mode is now supported ;)
     */
-	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
+	if (atomic_read(&dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding) &&
        !(ipv6_addr_type(&hdr->daddr) &
          (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
        likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 41cb348a7c3c..5f0ac47acc74 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -740,7 +740,7 @@ static int mif6_delete(struct mr_table *mrt, int vifi, int notify,
in6_dev = __in6_dev_get(dev);
    if (in6_dev) {
-		in6_dev->cnf.mc_forwarding--;
+		atomic_dec(&in6_dev->cnf.mc_forwarding);
    	inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
    				     NETCONFA_MC_FORWARDING,
    				     dev->ifindex, &in6_dev->cnf);
@@ -908,7 +908,7 @@ static int mif6_add(struct net *net, struct mr_table *mrt,
in6_dev = __in6_dev_get(dev);
    if (in6_dev) {
-		in6_dev->cnf.mc_forwarding++;
+		atomic_inc(&in6_dev->cnf.mc_forwarding);
    	inet6_netconf_notify_devconf(dev_net(dev), RTM_NEWNETCONF,
    				     NETCONFA_MC_FORWARDING,
    				     dev->ifindex, &in6_dev->cnf);
@@ -1558,7 +1558,7 @@ static int ip6mr_sk_init(struct mr_table *mrt, struct sock *sk)
    } else {
    	rcu_assign_pointer(mrt->mroute_sk, sk);
    	sock_set_flag(sk, SOCK_RCU_FREE);
-		net->ipv6.devconf_all->mc_forwarding++;
+		atomic_inc(&net->ipv6.devconf_all->mc_forwarding);
    }
    write_unlock_bh(&mrt_lock);
@@ -1591,7 +1591,7 @@ int ip6mr_sk_done(struct sock *sk)
    		 * so the RCU grace period before sk freeing
    		 * is guaranteed by sk_destruct()
    		 */
-			net->ipv6.devconf_all->mc_forwarding--;
+			atomic_dec(&net->ipv6.devconf_all->mc_forwarding);
    		write_unlock_bh(&mrt_lock);
    		inet6_netconf_notify_devconf(net, RTM_NEWNETCONF,
    					     NETCONFA_MC_FORWARDING,
-- 
2.34.1

    