From dad9b335c6940de2746a9788eb456d09cf102f81 Mon Sep 17 00:00:00 2001 From: Wang Chen Date: Wed, 18 Jun 2008 01:48:28 -0700 Subject: 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: Wang Chen Acked-by: Patrick McHardy Signed-off-by: David S. Miller --- net/core/dev.c | 55 +++++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 45 insertions(+), 10 deletions(-) (limited to 'net') diff --git a/net/core/dev.c b/net/core/dev.c index 0e45742e715..a495f712d38 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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->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->flags &= ~IFF_ALLMULTI; + 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; } /* -- cgit v1.2.3