[PATCH net 3/3] netfilter: ipset: Fix race between IPSET_CMD_CREATE and IPSET_CMD_SWAP
From: Florian Westphal <fw@strlen.de>
Date: 2023-09-20 08:42:18
Also in:
netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Jozsef Kadlecsik <redacted>
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 <redacted>
Closes: https://lore.kernel.org/netfilter-devel/ZPZqetxOmH+w%2Fmyc@westworld/#r (local)
Tested-by: Kyle Zeng <redacted>
Signed-off-by: Jozsef Kadlecsik <redacted>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
net/netfilter/ipset/ip_set_core.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index e564b5174261..35d2f9c9ada0 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c@@ -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);
--
2.41.0