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IPv6: fix race between cleanup and add/delete address

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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: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
stephen hemminger 2010-03-03 08:19:59 +00:00 committed by David S. Miller
parent 84e8b803f1
commit 8f37ada5b5
1 changed files with 13 additions and 5 deletions
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18
net/ipv6/addrconf.c
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@ -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 */