On Fri, Jan 27, 2006 at 01:00:49AM -0700, Eric W. Biederman wrote:
>
> However I do know I have correctly found the leak.
Yes you are right. The locking/refcounting in addrconf.c is such
a mess. I've asked a number of times before as to why most of
this can't be done in user-space instead. There is nothing performance
critical here, and the system must be able to deal with a device with
no IPv6 addresses anyway (think of the case when the device was up before
ipv6.ko was loaded). I'm yet to hear a compelling reason. Anyway,
that's enough ranting from me and here is a patch for your bug.
[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 <[EMAIL PROTECTED]>
Cheers,
--
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3321,9 +3321,7 @@ static void __ipv6_ifa_notify(int event,
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,
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;
}
}
