Commit 02a23398 authored Sep 19, 2023 by Jozsef Kadlecsik Committed by Greg Kroah-Hartman Oct 10, 2023

netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP



[ Upstream commit 7433b6d2afd512d04398c73aa984d1e285be125b ]

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: 24e227896bbf ("netfilter: ipset: Add schedule point in call_ad().")
Reported-by: Kyle Zeng <zengyhkyle@gmail.com>
Closes: https://lore.kernel.org/netfilter-devel/ZPZqetxOmH+w%2Fmyc@westworld/#r


Tested-by: Kyle Zeng <zengyhkyle@gmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 812da2a0

net/netfilter/ipset/ip_set_core.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -530,6 +530,14 @@ __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 inline void
		__ip_set_put_netlink(struct ip_set *set)
		{
		@@ -1529,11 +1537,11 @@ call_ad(struct sock ctnl, struct sk_buff skb, struct ip_set *set,

		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);