Patch "net: bridge: start hello timer only if device is up" has been added to the 4.4-stable tree

Patch "net: bridge: start hello timer only if device is up" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net: bridge: start hello timer only if device is up

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-bridge-start-hello-timer-only-if-device-is-up.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Jun  8 09:11:25 CEST 2017
From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Date: Thu, 1 Jun 2017 18:07:55 +0300
Subject: net: bridge: start hello timer only if device is up

From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>


[ Upstream commit aeb073241fe7a2b932e04e20c60e47718332877f ]

When the transition of NO_STP -> KERNEL_STP was fixed by always calling
mod_timer in br_stp_start, it introduced a new regression which causes
the timer to be armed even when the bridge is down, and since we stop
the timers in its ndo_stop() function, they never get disabled if the
device is destroyed before it's upped.

To reproduce:
$ while :; do ip l add br0 type bridge hello_time 100; brctl stp br0 on;
ip l del br0; done;

CC: Xin Long <lucien.xin@gmail.com>
CC: Ivan Vecera <cera@cera.cz>
CC: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Fixes: 6d18c732b95c ("bridge: start hello_timer when enabling KERNEL_STP in br_stp_start")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/bridge/br_stp_if.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/bridge/br_stp_if.c
+++ b/net/bridge/br_stp_if.c
@@ -166,7 +166,8 @@ static void br_stp_start(struct net_brid
 		br_debug(br, "using kernel STP\n");
 
 		/* To start timers on any ports left in blocking */
-		mod_timer(&br->hello_timer, jiffies + br->hello_time);
+		if (br->dev->flags & IFF_UP)
+			mod_timer(&br->hello_timer, jiffies + br->hello_time);
 		br_port_state_selection(br);
 	}
 


Patches currently in stable-queue which might be from nikolay@cumulusnetworks.com are

queue-4.4/net-bridge-start-hello-timer-only-if-device-is-up.patch