netdev - [PATCH] bridge: prevent bridging wrong device

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Message-ID: <20091104094713.1983a0b6@nehalam>
Date:	Wed, 4 Nov 2009 09:47:13 -0800
From:	Stephen Hemminger <shemminger@...tta.com>
To:	David Miller <davem@...emloft.net>
Cc:	nneul@....edu, netdev@...r.kernel.org
Subject: [PATCH]  bridge: prevent bridging wrong device


The bridge code assumes ethernet addressing, so be more strict in
the what is allowed. This showed up when GRE had a bug and was not
using correct address format.

Add some more comments for increased clarity.

Signed-off-by: Stephen Hemminger <shemminger@...tta.com>

--- a/net/bridge/br_if.c	2009-10-29 15:18:48.363916679 -0700
+++ b/net/bridge/br_if.c	2009-11-03 19:39:17.733252912 -0800
@@ -377,12 +377,16 @@ int br_add_if(struct net_bridge *br, str
 	struct net_bridge_port *p;
 	int err = 0;
 
-	if (dev->flags & IFF_LOOPBACK || dev->type != ARPHRD_ETHER)
+	/* Don't allow bridging non-ethernet like devices */
+	if ((dev->flags & IFF_LOOPBACK) ||
+	    dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN)
 		return -EINVAL;
 
+	/* No bridging of bridges */
 	if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)
 		return -ELOOP;
 
+	/* Device is already being bridged */
 	if (dev->br_port != NULL)
 		return -EBUSY;
 
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