Commit 7433b6d2 authored by Jozsef Kadlecsik's avatar Jozsef Kadlecsik Committed by Florian Westphal
Browse files

netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP 



Kyle Zeng reported that there is a race between IPSET_CMD_ADD and IPSET_CMD_SWAP
in netfilter/ip_set, which can lead to the invocation of `__ip_set_put` on a
wrong `set`, triggering the `BUG_ON(set->ref == 0);` check in it.

The race is caused by using the wrong reference counter, i.e. the ref counter instead
of ref_netlink.

Fixes: 24e22789 ("netfilter: ipset: Add schedule point in call_ad().")
Reported-by: default avatarKyle Zeng <zengyhkyle@gmail.com>
Closes: https://lore.kernel.org/netfilter-devel/ZPZqetxOmH+w%2Fmyc@westworld/#r


Tested-by: default avatarKyle Zeng <zengyhkyle@gmail.com>
Signed-off-by: default avatarJozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
parent cf5000a7

net/netfilter/ipset/ip_set_core.c

+10 −2
Original line number Diff line number Diff line
@@ -682,6 +682,14 @@ __ip_set_put(struct ip_set *set) 
/* set->ref can be swapped out by ip_set_swap, netlink events (like dump) need

 * a separate reference counter

 */

static void

__ip_set_get_netlink(struct ip_set *set)

{

	write_lock_bh(&ip_set_ref_lock);

	set->ref_netlink++;

	write_unlock_bh(&ip_set_ref_lock);

}



static void

__ip_set_put_netlink(struct ip_set *set)

{
@@ -1693,11 +1701,11 @@ call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb, 


	do {

		if (retried) {

			__ip_set_get(set);

			__ip_set_get_netlink(set);

			nfnl_unlock(NFNL_SUBSYS_IPSET);

			cond_resched();

			nfnl_lock(NFNL_SUBSYS_IPSET);

			__ip_set_put(set);

			__ip_set_put_netlink(set);

		}



		ip_set_lock(set);