Patch "net: core: Correct an over-stringent device loop detection." has been added to the 3.14-stable tree

Patch "net: core: Correct an over-stringent device loop detection." has been added to the 3.14-stable tree

[gregkh]

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

    net: core: Correct an over-stringent device loop detection.

to the 3.14-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-core-correct-an-over-stringent-device-loop-detection.patch
and it can be found in the queue-3.14 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 Sat Jun 13 09:49:06 PDT 2015
From: Vlad Yasevich <vyasevich@gmail.com>
Date: Sat, 2 May 2015 21:33:44 -0400
Subject: net: core: Correct an over-stringent device loop detection.

From: Vlad Yasevich <vyasevich@gmail.com>

[ Upstream commit d66bf7dd27573ee5ea90484899ee952c19ccb194 ]

The code in __netdev_upper_dev_link() has an over-stringent
loop detection logic that actually prevents valid configurations
from working correctly.

In particular, the logic returns an error if an upper device
is already in the list of all upper devices for a given dev.
This particular check seems to be a overzealous as it disallows
perfectly valid configurations.  For example:
  # ip l a link eth0 name eth0.10 type vlan id 10
  # ip l a dev br0 typ bridge
  # ip l s eth0.10 master br0
  # ip l s eth0 master br0  <--- Will fail

If you switch the last two commands (add eth0 first), then both
will succeed.  If after that, you remove eth0 and try to re-add
it, it will fail!

It appears to be enough to simply check adj_list to keeps things
safe.

I've tried stacking multiple devices multiple times in all different
combinations, and either rx_handler registration prevented the stacking
of the device linking cought the error.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Veaceslav Falico <vfalico@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/dev.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4903,7 +4903,7 @@ static int __netdev_upper_dev_link(struc
 	if (__netdev_find_adj(upper_dev, dev, &upper_dev->all_adj_list.upper))
 		return -EBUSY;
 
-	if (__netdev_find_adj(dev, upper_dev, &dev->all_adj_list.upper))
+	if (__netdev_find_adj(dev, upper_dev, &dev->adj_list.upper))
 		return -EEXIST;
 
 	if (master && netdev_master_upper_dev_get(dev))


Patches currently in stable-queue which might be from vyasevich@gmail.com are

queue-3.14/net-core-correct-an-over-stringent-device-loop-detection.patch