From: Wang Chen <wangchen@cn•fujitsu.com>
To: "David S. Miller" <davem@davemloft•net>
Cc: NETDEV <netdev@vger•kernel.org>
Subject: RFC: [PATCH 2/3] netdevice: Fix promiscuity and allmulti overflow
Date: Mon, 16 Jun 2008 17:15:49 +0800 [thread overview]
Message-ID: <48562F45.3040302@cn.fujitsu.com> (raw)
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 will make the counters touch the roof, we report error.
Signed-off-by: Wang Chen <wangchen@cn•fujitsu.com>
---
net/core/dev.c | 29 +++++++++++++++++++++++++----
1 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 5829630..a3c692d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2753,10 +2753,20 @@ static void __dev_set_promiscuity(struct net_device *dev, int inc)
ASSERT_RTNL();
+ dev->flags |= IFF_PROMISC;
if ((dev->promiscuity += inc) == 0)
- dev->flags &= ~IFF_PROMISC;
- else
- dev->flags |= IFF_PROMISC;
+ /*
+ * Avoid overflow.
+ * If inc causes overflow, ignore it and warn user.
+ */
+ if (inc < 0)
+ dev->flags &= ~IFF_PROMISC;
+ else {
+ dev->promiscuity -= inc;
+ printk(KERN_ERR "%s: promiscuity touches roof, "
+ "set promiscuity failed, promiscuity feature "
+ "of device will be broken.\n");
+ }
if (dev->flags != old_flags) {
printk(KERN_INFO "device %s %s promiscuous mode\n",
dev->name, (dev->flags & IFF_PROMISC) ? "entered" :
@@ -2815,7 +2825,18 @@ void dev_set_allmulti(struct net_device *dev, int inc)
dev->flags |= IFF_ALLMULTI;
if ((dev->allmulti += inc) == 0)
- dev->flags &= ~IFF_ALLMULTI;
+ /*
+ * Avoid overflow.
+ * If inc causes overflow, ignore it and warn user.
+ */
+ if (inc < 0)
+ dev->flags &= ~IFF_ALLMULTI;
+ else {
+ dev->allmulti -= inc;
+ printk(KERN_ERR "%s: allmulti touches roof, "
+ "set allmulti failed, allmulti feature of "
+ "device will be broken.\n");
+ }
if (dev->flags ^ old_flags) {
if (dev->change_rx_flags)
dev->change_rx_flags(dev, IFF_ALLMULTI);
--
1.5.3.4
next reply other threads:[~2008-06-16 9:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-16 9:15 Wang Chen [this message]
2008-06-16 9:38 ` RFC: [PATCH 2/3] netdevice: Fix promiscuity and allmulti overflow Patrick McHardy
2008-06-16 9:51 ` Wang Chen
2008-06-16 10:04 ` Patrick McHardy
2008-06-16 15:05 ` v2: " Wang Chen
2008-06-17 12:59 ` Patrick McHardy
2008-06-18 1:51 ` Wang Chen
2008-06-18 4:54 ` David Miller
2008-06-18 8:44 ` Patrick McHardy
2008-06-18 8:49 ` David Miller
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