linux-kernel - [PATCH 4.14 02/45] bridge: check iface upper dev when setting master via ioctl

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Message-Id: <20180518081530.441456191@linuxfoundation.org>
Date:   Fri, 18 May 2018 10:15:19 +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,
        syzbot+de73361ee4971b6e6f75@...kaller.appspotmail.com,
        Hangbin Liu <liuhangbin@...il.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.14 02/45] bridge: check iface upper dev when setting master via ioctl

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

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

From: Hangbin Liu <liuhangbin@...il.com>

[ Upstream commit e8238fc2bd7b4c3c7554fa2df067e796610212fc ]

When we set a bond slave's master to bridge via ioctl, we only check
the IFF_BRIDGE_PORT flag. Although we will find the slave's real master
at netdev_master_upper_dev_link() later, it already does some settings
and allocates some resources. It would be better to return as early
as possible.

v1 -> v2:
use netdev_master_upper_dev_get() instead of netdev_has_any_upper_dev()
to check if we have a master, because not all upper devs are masters,
e.g. vlan device.

Reported-by: syzbot+de73361ee4971b6e6f75@...kaller.appspotmail.com
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
Acked-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_if.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -503,8 +503,8 @@ int br_add_if(struct net_bridge *br, str
 	if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)
 		return -ELOOP;
 
-	/* Device is already being bridged */
-	if (br_port_exists(dev))
+	/* Device has master upper dev */
+	if (netdev_master_upper_dev_get(dev))
 		return -EBUSY;
 
 	/* No bridging devices that dislike that (e.g. wireless) */