ipv6: check for ip6_null_entry in __ip6_del_rt_siblings() (e3330039) · Commits · 戴 / test

Andrey reported a NULL pointer deref bug in ipv6_route_ioctl() -> ip6_route_del() -> __ip6_del_rt_siblings() code path. This is because ip6_null_entry is returned in this path since ip6_null_entry is kinda default for a ipv6 route table root node. Quote from David Ahern: ip6_null_entry is the root of all ipv6 fib tables making it integrated into the table ... We should ignore any attempt of trying to delete it, like we do in __ip6_del_rt() path and several others. Reported-by:

Andrey Konovalov <andreyknvl@google.com> Fixes: ("net: ipv6: Allow shorthand delete of all nexthops in multipath route") Cc: David Ahern <dsa@cumulusnetworks.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by:

Cong Wang <xiyou.wangcong@gmail.com> Acked-by:

David Ahern <dsa@cumulusnetworks.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv6/route.c

+9 −5

Original line number	Diff line number	Diff line
		@@ -2169,10 +2169,13 @@ int ip6_del_rt(struct rt6_info *rt)
		static int __ip6_del_rt_siblings(struct rt6_info rt, struct fib6_config cfg)
		{
		struct nl_info *info = &cfg->fc_nlinfo;
		struct net *net = info->nl_net;
		struct sk_buff *skb = NULL;
		struct fib6_table *table;
		int err;
		int err = -ENOENT;

		if (rt == net->ipv6.ip6_null_entry)
		goto out_put;
		table = rt->rt6i_table;
		write_lock_bh(&table->tb6_lock);

		@@ -2184,7 +2187,7 @@ static int __ip6_del_rt_siblings(struct rt6_info rt, struct fib6_config cfg)
		if (skb) {
		u32 seq = info->nlh ? info->nlh->nlmsg_seq : 0;

		if (rt6_fill_node(info->nl_net, skb, rt,
		if (rt6_fill_node(net, skb, rt,
		NULL, NULL, 0, RTM_DELROUTE,
		info->portid, seq, 0) < 0) {
		kfree_skb(skb);
		@@ -2198,17 +2201,18 @@ static int __ip6_del_rt_siblings(struct rt6_info rt, struct fib6_config cfg)
		rt6i_siblings) {
		err = fib6_del(sibling, info);
		if (err)
		goto out;
		goto out_unlock;
		}
		}

		err = fib6_del(rt, info);
		out:
		out_unlock:
		write_unlock_bh(&table->tb6_lock);
		out_put:
		ip6_rt_put(rt);

		if (skb) {
		rtnl_notify(skb, info->nl_net, info->portid, RTNLGRP_IPV6_ROUTE,
		rtnl_notify(skb, net, info->portid, RTNLGRP_IPV6_ROUTE,
		info->nlh, gfp_any());
		}
		return err;

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