From: Herbert Xu Date: Fri, 3 Feb 2006 00:55:45 +0000 (-0800) Subject: [IPV6]: Don't hold extra ref count in ipv6_ifa_notify X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=4641e7a334adf6856300a98e7296dfc886c446af;p=linux-beck.git [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 Signed-off-by: David S. Miller --- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index d328d5986143..1db50487916b 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; } }