[PATCH net] bridge: avoid OOPS if root port not found

[PATCH net] bridge: avoid OOPS if root port not found

[Stephen Hemminger]

Bridge can crash while trying to send topology change packet.
This happens if root port can't be found. This was reported by user
but currently unable to reproduce it easily. The STP conditions that cause
this are not known yet, but the problem doesn't have to be fatal.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>


--- a/net/bridge/br_stp.c	2013-03-07 18:12:53.885287247 -0800
+++ b/net/bridge/br_stp.c	2013-04-30 08:24:05.935771645 -0700
@@ -225,7 +225,14 @@ static void br_record_config_timeout_val
 /* called under bridge lock */
 void br_transmit_tcn(struct net_bridge *br)
 {
-	br_send_tcn_bpdu(br_get_port(br, br->root_port));
+	struct net_bridge_port *p;
+
+	p = br_get_port(br, br->root_port);
+	if (p)
+		br_send_tcn_bpdu(p);
+	else
+		br_notice(br, "root port %u not found for topology notice\n",
+			  br->root_port);
 }
 
 /* called under bridge lock */

Re: [PATCH net] bridge: avoid OOPS if root port not found

[David Miller]

From: Stephen Hemminger <stephen@networkplumber.org>
Date: Tue, 30 Apr 2013 08:29:27 -0700

> Bridge can crash while trying to send topology change packet.
> This happens if root port can't be found. This was reported by user
> but currently unable to reproduce it easily. The STP conditions that cause
> this are not known yet, but the problem doesn't have to be fatal.
> 
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

Right, there's no reason we should flat-out crash because of this.

Applied, thanks.