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Commit dad9b335 authored by Wang Chen's avatar Wang Chen Committed by David S. Miller
Browse files

netdevice: Fix promiscuity and allmulti overflow 



Max of promiscuity and allmulti plus positive @inc can cause overflow.
Fox example: when allmulti=0xFFFFFFFF, any caller give dev_set_allmulti() a
positive @inc will cause allmulti be off.
This is not what we want, though it's rare case.
The fix is that only negative @inc will cause allmulti or promiscuity be off
and when any caller makes the counters touch the roof, we return error.

Change of v2:
Change void function dev_set_promiscuity/allmulti to return int.
So callers can get the overflow error.
Caller's fix will be done later.

Change of v3:
1. Since we return error to caller, we don't need to print KERN_ERROR,
KERN_WARNING is enough.
2. In dev_set_promiscuity(), if __dev_set_promiscuity() failed, we
return at once.

Signed-off-by: default avatarWang Chen <wangchen@cn.fujitsu.com>
Acked-by: default avatarPatrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dd574dbf

include/linux/netdevice.h

+2 −2
Original line number Diff line number Diff line
@@ -1476,8 +1476,8 @@ extern int __dev_addr_delete(struct dev_addr_list **list, int *count, void *ad 
extern int		__dev_addr_add(struct dev_addr_list **list, int *count, void *addr, int alen, int newonly);

extern int		__dev_addr_sync(struct dev_addr_list **to, int *to_count, struct dev_addr_list **from, int *from_count);

extern void		__dev_addr_unsync(struct dev_addr_list **to, int *to_count, struct dev_addr_list **from, int *from_count);

extern void		dev_set_promiscuity(struct net_device *dev, int inc);

extern void		dev_set_allmulti(struct net_device *dev, int inc);

extern int		dev_set_promiscuity(struct net_device *dev, int inc);

extern int		dev_set_allmulti(struct net_device *dev, int inc);

extern void		netdev_state_change(struct net_device *dev);

extern void		netdev_bonding_change(struct net_device *dev);

extern void		netdev_features_change(struct net_device *dev);

net/core/dev.c

+45 −10
Original line number Diff line number Diff line
@@ -2771,16 +2771,29 @@ int netdev_set_master(struct net_device *slave, struct net_device *master) 
	return 0;

}



static void __dev_set_promiscuity(struct net_device *dev, int inc)

static int __dev_set_promiscuity(struct net_device *dev, int inc)

{

	unsigned short old_flags = dev->flags;



	ASSERT_RTNL();



	if ((dev->promiscuity += inc) == 0)

		dev->flags &= ~IFF_PROMISC;

	else

	dev->flags |= IFF_PROMISC;

	dev->promiscuity += inc;

	if (dev->promiscuity == 0) {

		/*

		 * Avoid overflow.

		 * If inc causes overflow, untouch promisc and return error.

		 */

		if (inc < 0)

			dev->flags &= ~IFF_PROMISC;

		else {

			dev->promiscuity -= inc;

			printk(KERN_WARNING "%s: promiscuity touches roof, "

				"set promiscuity failed, promiscuity feature "

				"of device might be broken.\n", dev->name);

			return -EOVERFLOW;

		}

	}

	if (dev->flags != old_flags) {

		printk(KERN_INFO "device %s %s promiscuous mode\n",

		       dev->name, (dev->flags & IFF_PROMISC) ? "entered" :
@@ -2798,6 +2811,7 @@ static void __dev_set_promiscuity(struct net_device *dev, int inc) 
		if (dev->change_rx_flags)

			dev->change_rx_flags(dev, IFF_PROMISC);

	}

	return 0;

}



/**
@@ -2809,14 +2823,19 @@ static void __dev_set_promiscuity(struct net_device *dev, int inc) 
 *	remains above zero the interface remains promiscuous. Once it hits zero

 *	the device reverts back to normal filtering operation. A negative inc

 *	value is used to drop promiscuity on the device.

 *	Return 0 if successful or a negative errno code on error.

 */

void dev_set_promiscuity(struct net_device *dev, int inc)

int dev_set_promiscuity(struct net_device *dev, int inc)

{

	unsigned short old_flags = dev->flags;

	int err;



	__dev_set_promiscuity(dev, inc);

	err = __dev_set_promiscuity(dev, inc);

	if (!err)

		return err;

	if (dev->flags != old_flags)

		dev_set_rx_mode(dev);

	return err;

}



/**
@@ -2829,22 +2848,38 @@ void dev_set_promiscuity(struct net_device *dev, int inc) 
 *	to all interfaces. Once it hits zero the device reverts back to normal

 *	filtering operation. A negative @inc value is used to drop the counter

 *	when releasing a resource needing all multicasts.

 *	Return 0 if successful or a negative errno code on error.

 */



void dev_set_allmulti(struct net_device *dev, int inc)

int dev_set_allmulti(struct net_device *dev, int inc)

{

	unsigned short old_flags = dev->flags;



	ASSERT_RTNL();



	dev->flags |= IFF_ALLMULTI;

	if ((dev->allmulti += inc) == 0)

	dev->allmulti += inc;

	if (dev->allmulti == 0) {

		/*

		 * Avoid overflow.

		 * If inc causes overflow, untouch allmulti and return error.

		 */

		if (inc < 0)

			dev->flags &= ~IFF_ALLMULTI;

		else {

			dev->allmulti -= inc;

			printk(KERN_WARNING "%s: allmulti touches roof, "

				"set allmulti failed, allmulti feature of "

				"device might be broken.\n", dev->name);

			return -EOVERFLOW;

		}

	}

	if (dev->flags ^ old_flags) {

		if (dev->change_rx_flags)

			dev->change_rx_flags(dev, IFF_ALLMULTI);

		dev_set_rx_mode(dev);

	}

	return 0;

}



/*