From e3330039ea28dc199e3b2da993895ff742a91adf Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Mon, 27 Feb 2017 16:07:43 -0800 Subject: [PATCH] ipv6: check for ip6_null_entry in __ip6_del_rt_siblings() 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 Fixes: 0ae8133586ad ("net: ipv6: Allow shorthand delete of all nexthops in multipath route") Cc: David Ahern Cc: Eric Dumazet Signed-off-by: Cong Wang Acked-by: David Ahern Signed-off-by: David S. Miller --- net/ipv6/route.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index d94f1dfa54c8..43ca90d50ae9 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -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;