[PATCH 5.13 1/2] net: bridge: multicast: fix PIM hello router port marking race

[PATCH 5.13 1/2] net: bridge: multicast: fix PIM hello router port marking race

[Nikolay Aleksandrov]

From: Nikolay Aleksandrov <nikolay@nvidia.com>

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>
---
 net/bridge/br_multicast.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 226bb05c3b42..e27fe6e6ecd4 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -3087,7 +3087,9 @@ 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_ip4_multicast_mrd_rcv(struct net_bridge *br,
-- 
2.31.1

[PATCH 5.13 2/2] net: bridge: multicast: fix MRD advertisement router port marking race

[Nikolay Aleksandrov]

From: Nikolay Aleksandrov <nikolay@nvidia.com>

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>
---
 net/bridge/br_multicast.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index e27fe6e6ecd4..869f1608c98a 100644
--- 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,
-- 
2.31.1

Re: [PATCH 5.13 1/2] net: bridge: multicast: fix PIM hello router port marking race

[Greg KH]

On Mon, Jul 19, 2021 at 03:53:54PM +0300, Nikolay Aleksandrov wrote:
> From: Nikolay Aleksandrov <nikolay@nvidia.com>
> 
> 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>
> ---
>  net/bridge/br_multicast.c | 2 ++
>  1 file changed, 2 insertions(+)

Thanks for the backports, all now queued up.

greg k-h