net: bridge: multicast: fix MRD advertisement router port marking race

commit 000b7287b67555fee39d39fff75229dedde0dcbf upstream.

When an MRD advertisement is received on a bridge port with multicast
snooping enabled, we mark it as a router port automatically, that
includes adding that port to the router port list. The multicast lock
protects that list, but it is not acquired in the MRD advertisement case
leading to a race condition, we need to take it to fix the race.

Cc: stable@vger.kernel.org
Cc: linus.luessing@c0d3.blue
Fixes: 4b3087c7e37f ("bridge: Snoop Multicast Router Advertisements")
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index e27fe6e6ecd400fb39e4ece61fdc9a609b7e6fd3..869f1608c98a34af12693d3ecd1dcaba7500565a 100644 (file)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3100,7 +3100,9 @@ static int br_ip4_multicast_mrd_rcv(struct net_bridge *br,
            igmp_hdr(skb)->type != IGMP_MRDISC_ADV)
                return -ENOMSG;
 
+       spin_lock(&br->multicast_lock);
        br_multicast_mark_router(br, port);
+       spin_unlock(&br->multicast_lock);
 
        return 0;
 }
@@ -3168,7 +3170,9 @@ static void br_ip6_multicast_mrd_rcv(struct net_bridge *br,
        if (icmp6_hdr(skb)->icmp6_type != ICMPV6_MRDISC_ADV)
                return;
 
+       spin_lock(&br->multicast_lock);
        br_multicast_mark_router(br, port);
+       spin_unlock(&br->multicast_lock);
 }
 
 static int br_multicast_ipv6_rcv(struct net_bridge *br,