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Commit 8f37ada5 authored by stephen hemminger's avatar stephen hemminger Committed by David S. Miller
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IPv6: fix race between cleanup and add/delete address 



This solves a potential race problem during the cleanup process.
The issue is that addrconf_ifdown() needs to traverse address list,
but then drop lock to call the notifier. The version in -next
could get confused if add/delete happened during this window.
Original code (2.6.32 and earlier) was okay because all addresses
were always deleted.

Signed-off-by: default avatarStephen Hemminger <shemminger@vyatta.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 84e8b803

net/ipv6/addrconf.c

+13 −5
Original line number Diff line number Diff line
@@ -2615,7 +2615,7 @@ static void addrconf_bonding_change(struct net_device *dev, unsigned long event) 
static int addrconf_ifdown(struct net_device *dev, int how)

{

	struct inet6_dev *idev;

	struct inet6_ifaddr *ifa, **bifa;

	struct inet6_ifaddr *ifa, *keep_list, **bifa;

	struct net *net = dev_net(dev);

	int i;
@@ -2689,8 +2689,12 @@ static int addrconf_ifdown(struct net_device *dev, int how) 
		write_lock_bh(&idev->lock);

	}

#endif

	bifa = &idev->addr_list;

	while ((ifa = *bifa) != NULL) {

	keep_list = NULL;

	bifa = &keep_list;

	while ((ifa = idev->addr_list) != NULL) {

		idev->addr_list = ifa->if_next;

		ifa->if_next = NULL;



		addrconf_del_timer(ifa);



		/* If just doing link down, and address is permanent
@@ -2698,6 +2702,9 @@ static int addrconf_ifdown(struct net_device *dev, int how) 
		if (how == 0 &&

		    (ifa->flags&IFA_F_PERMANENT) &&

		    !(ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)) {



			/* Move to holding list */

			*bifa = ifa;

			bifa = &ifa->if_next;



			/* If not doing DAD on this address, just keep it. */
@@ -2714,8 +2721,6 @@ static int addrconf_ifdown(struct net_device *dev, int how) 
			ifa->flags |= IFA_F_TENTATIVE;

			in6_ifa_hold(ifa);

		} else {

			*bifa = ifa->if_next;

			ifa->if_next = NULL;

			ifa->dead = 1;

		}

		write_unlock_bh(&idev->lock);
@@ -2726,6 +2731,9 @@ static int addrconf_ifdown(struct net_device *dev, int how) 


		write_lock_bh(&idev->lock);

	}



	idev->addr_list = keep_list;



	write_unlock_bh(&idev->lock);



	/* Step 5: Discard multicast list */