Linux Ethernet Bridging - May 2015 - [Bridge] [PATCH net] bridge: fix br_multicast_query_expired() bug

From: Eric Dumazet <edumazet at google.com>

br_multicast_query_expired() querier argument is a pointer to
a struct bridge_mcast_querier :

struct bridge_mcast_querier {
        struct br_ip addr;
        struct net_bridge_port __rcu    *port;
};

Intent of the code was to clear port field, not the pointer to querier.

Fixes: 2cd4143192e8 ("bridge: memorize and export selected IGMP/MLD querier
port")
Signed-off-by: Eric Dumazet <edumazet at google.com>
Cc: Linus L?ssing <linus.luessing at web.de>
Cc: Steinar H. Gunderson <sesse at samfundet.no>
---
 net/bridge/br_multicast.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index a3abe6ed111e..22fd0419b314 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1822,7 +1822,7 @@ static void br_multicast_query_expired(struct net_bridge
*br,
 	if (query->startup_sent < br->multicast_startup_query_count)
 		query->startup_sent++;
 
-	RCU_INIT_POINTER(querier, NULL);
+	RCU_INIT_POINTER(querier->port, NULL);
 	br_multicast_send_query(br, NULL, query);
 	spin_unlock(&br->multicast_lock);
 }

On Thu, May 28, 2015 at 04:42:54AM -0700, Eric Dumazet
wrote:
> From: Eric Dumazet <edumazet at google.com>
> 
> br_multicast_query_expired() querier argument is a pointer to
> a struct bridge_mcast_querier :
> 
> struct bridge_mcast_querier {
>         struct br_ip addr;
>         struct net_bridge_port __rcu    *port;
> };
> 
> Intent of the code was to clear port field, not the pointer to querier.
> 
> Fixes: 2cd4143192e8 ("bridge: memorize and export selected IGMP/MLD
querier port")
> Signed-off-by: Eric Dumazet <edumazet at google.com>
> Cc: Linus L?ssing <linus.luessing at web.de>
> Cc: Steinar H. Gunderson <sesse at samfundet.no>
> ---
>  net/bridge/br_multicast.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
> index a3abe6ed111e..22fd0419b314 100644
> --- a/net/bridge/br_multicast.c
> +++ b/net/bridge/br_multicast.c
> @@ -1822,7 +1822,7 @@ static void br_multicast_query_expired(struct
net_bridge *br,
>  	if (query->startup_sent < br->multicast_startup_query_count)
>  		query->startup_sent++;
>  
> -	RCU_INIT_POINTER(querier, NULL);
> +	RCU_INIT_POINTER(querier->port, NULL);
>  	br_multicast_send_query(br, NULL, query);
>  	spin_unlock(&br->multicast_lock);
>  }
> 
> 
> 
> --
Acked-by: Thadeu Lima de Souza Cascardo <cascardo at redhat.com>

On Thu, May 28, 2015 at 04:42:54AM -0700, Eric Dumazet
wrote:
> Intent of the code was to clear port field, not the pointer to querier.
Acked-by: Linus L?ssing <linus.luessing at c0d3.blue>

From: Eric Dumazet <eric.dumazet at gmail.com>
Date: Thu, 28 May 2015 04:42:54 -0700
> From: Eric Dumazet <edumazet at google.com>
> 
> br_multicast_query_expired() querier argument is a pointer to
> a struct bridge_mcast_querier :
> 
> struct bridge_mcast_querier {
>         struct br_ip addr;
>         struct net_bridge_port __rcu    *port;
> };
> 
> Intent of the code was to clear port field, not the pointer to querier.
> 
> Fixes: 2cd4143192e8 ("bridge: memorize and export selected IGMP/MLD
querier port")
> Signed-off-by: Eric Dumazet <edumazet at google.com>
Applied, thanks Eric.