linux-kernel - [PATCH 4.11 002/150] net: bridge: start hello timer only if device is up

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Date:   Mon, 12 Jun 2017 17:23:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xin Long <lucien.xin@...il.com>,
        Ivan Vecera <cera@...a.cz>,
        Sebastian Ott <sebott@...ux.vnet.ibm.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.11 002/150] net: bridge: start hello timer only if device is up

4.11-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <nikolay@...ulusnetworks.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@...il.com>
CC: Ivan Vecera <cera@...a.cz>
CC: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Reported-by: Sebastian Ott <sebott@...ux.vnet.ibm.com>
Fixes: 6d18c732b95c ("bridge: start hello_timer when enabling KERNEL_STP in br_stp_start")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -179,7 +179,8 @@ 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);
 	}