netdev - [patch -stable] igbvf: integer wrapping bug setting the mtu

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Message-ID: <20130913083736.GK19211@elgon.mountain>
Date:	Fri, 13 Sep 2013 11:37:36 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:	Jesse Brandeburg <jesse.brandeburg@...el.com>,
	Bruce Allan <bruce.w.allan@...el.com>,
	Carolyn Wyborny <carolyn.wyborny@...el.com>,
	Don Skidmore <donald.c.skidmore@...el.com>,
	Greg Rose <gregory.v.rose@...el.com>,
	Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com>,
	Alex Duyck <alexander.h.duyck@...el.com>,
	John Ronciak <john.ronciak@...el.com>,
	Tushar Dave <tushar.n.dave@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	Mitch Williams <mitch.a.williams@...el.com>,
	Patrick McHardy <kaber@...sh.net>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	e1000-devel@...ts.sourceforge.net, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: [patch -stable] igbvf: integer wrapping bug setting the mtu

If new_mtu is very large then "new_mtu + ETH_HLEN + ETH_FCS_LEN" can
wrap and the check on the next line can underflow. This is one of those
bugs which can be triggered by the user if you have namespaces
configured.

This is a static checker fix and I'm not sure what the impact is.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c
index 95d5430..24e3883 100644
--- a/drivers/net/ethernet/intel/igbvf/netdev.c
+++ b/drivers/net/ethernet/intel/igbvf/netdev.c
@@ -2342,7 +2342,7 @@ static struct net_device_stats *igbvf_get_stats(struct net_device *netdev)
 static int igbvf_change_mtu(struct net_device *netdev, int new_mtu)
 {
 	struct igbvf_adapter *adapter = netdev_priv(netdev);
-	int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN;
+	unsigned int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN;
 
 	if ((new_mtu < 68) || (max_frame > MAX_JUMBO_FRAME_SIZE)) {
 		dev_err(&adapter->pdev->dev, "Invalid MTU setting\n");
--
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