From 3840538ad384fb7891adeeaf36624f870c51fc0e Mon Sep 17 00:00:00 2001 From: Sabrina Dubroca Date: Tue, 18 Jul 2017 14:56:17 +0200 Subject: [PATCH] netfilter: ipt_CLUSTERIP: fix use-after-free of proc entry When we delete a netns with a CLUSTERIP rule, clusterip_net_exit() is called first, removing /proc/net/ipt_CLUSTERIP. Then clusterip_config_entry_put() is called from clusterip_tg_destroy(), and tries to remove its entry under /proc/net/ipt_CLUSTERIP/. Fix this by checking that the parent directory of the entry to remove hasn't already been deleted. The following triggers a KASAN splat (stealing the reproducer from 202f59afd441, thanks to Jianlin Shi and Xin Long): ip netns add test ip link add veth0_in type veth peer name veth0_out ip link set veth0_in netns test ip netns exec test ip link set lo up ip netns exec test ip link set veth0_in up ip netns exec test iptables -I INPUT -d 1.2.3.4 -i veth0_in -j \ CLUSTERIP --new --clustermac 89:d4:47:eb:9a:fa --total-nodes 3 \ --local-node 1 --hashmode sourceip-sourceport ip netns del test Fixes: ce4ff76c15a8 ("netfilter: ipt_CLUSTERIP: make proc directory per net namespace") Signed-off-by: Sabrina Dubroca Reviewed-by: Xin Long Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 7d72dec..efaa04d 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -117,7 +117,8 @@ clusterip_config_entry_put(struct net *net, struct clusterip_config *c) * functions are also incrementing the refcount on their own, * so it's safe to remove the entry even if it's in use. */ #ifdef CONFIG_PROC_FS - proc_remove(c->pde); + if (cn->procdir) + proc_remove(c->pde); #endif return; } @@ -815,6 +816,7 @@ static void clusterip_net_exit(struct net *net) #ifdef CONFIG_PROC_FS struct clusterip_net *cn = net_generic(net, clusterip_net_id); proc_remove(cn->procdir); + cn->procdir = NULL; #endif nf_unregister_net_hook(net, &cip_arp_ops); } -- 2.7.4