net: bridge: multicast: fix PIM hello router port marking race

commit 04bef83a3358946bfc98a5ecebd1b0003d83d882 upstream.

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

Cc: stable@vger.kernel.org
Fixes: 91b02d3d133b ("bridge: mcast: add router port on PIM hello message")
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 6a362da211e1b45aa5e7b94a8085217ab707023f..3504c3acd38f66385e1a64e17d7de8543be94805 100644 (file)
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1791,7 +1791,9 @@ static void br_multicast_pim(struct net_bridge *br,
            pim_hdr_type(pimhdr) != PIM_TYPE_HELLO)
                return;
 
+       spin_lock(&br->multicast_lock);
        br_multicast_mark_router(br, port);
+       spin_unlock(&br->multicast_lock);
 }
 
 static int br_multicast_ipv4_rcv(struct net_bridge *br,