From 4641e7a334adf6856300a98e7296dfc886c446af Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 2 Feb 2006 16:55:45 -0800
Subject: [PATCH] [IPV6]: Don't hold extra ref count in ipv6_ifa_notify
Currently the logic in ipv6_ifa_notify is to hold an extra reference
count for addrconf dst's that get added to the routing table. Thus,
when addrconf dst entries are taken out of the routing table, we need
to drop that dst. However, addrconf dst entries may be removed from
the routing table by means other than __ipv6_ifa_notify.
So we're faced with the choice of either fixing up all places where
addrconf dst entries are removed, or dropping the extra reference count
altogether.
I chose the latter because the ifp itself always holds a dst reference
count of 1 while it's alive. This is dropped just before we kfree the
ifp object. Therefore we know that in __ipv6_ifa_notify we will always
hold that count.
This bug was found by Eric W. Biederman.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv6/addrconf.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d328d59861438..1db50487916bf 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3321,9 +3321,7 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
switch (event) {
case RTM_NEWADDR:
- dst_hold(&ifp->rt->u.dst);
- if (ip6_ins_rt(ifp->rt, NULL, NULL, NULL))
- dst_release(&ifp->rt->u.dst);
+ ip6_ins_rt(ifp->rt, NULL, NULL, NULL);
if (ifp->idev->cnf.forwarding)
addrconf_join_anycast(ifp);
break;
@@ -3334,8 +3332,6 @@ static void __ipv6_ifa_notify(int event, struct inet6_ifaddr *ifp)
dst_hold(&ifp->rt->u.dst);
if (ip6_del_rt(ifp->rt, NULL, NULL, NULL))
dst_free(&ifp->rt->u.dst);
- else
- dst_release(&ifp->rt->u.dst);
break;
}
}
--
2.30.2