[PATCH 6.12 182/242] netfilter: ipset: drop logically empty buckets in mtype_del

Greg Kroah-Hartman
2026-04-08T18:47:07Z

From: Yifan Wu <yifanwucs@gmail.com>

commit 9862ef9ab0a116c6dca98842aab7de13a252ae02 upstream.

mtype_del() counts empty slots below n->pos in k, but it only drops the
bucket when both n->pos and k are zero. This misses buckets whose live
entries have all been removed while n->pos still points past deleted slots.

Treat a bucket as empty when all positions below n->pos are unused and
release it directly instead of shrinking it further.

Fixes: 8af1c6fbd923 ("netfilter: ipset: Fix forceadd evaluation path")
Cc: stable@vger.kernel.org
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <dstsmallbird@foxmail.com>
Signed-off-by: Yifan Wu <yifanwucs@gmail.com>
Co-developed-by: Yuan Tan <yuantan098@gmail.com>
Signed-off-by: Yuan Tan <yuantan098@gmail.com>
Reviewed-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/ipset/ip_set_hash_gen.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -1099,7 +1099,7 @@ mtype_del(struct ip_set *set, void *valu
if (!test_bit(i, n->used))
k++;
}
- if (n->pos == 0 && k == 0) {
+ if (k == n->pos) {
t->hregion[r].ext_size -= ext_size(n->size, dsize);
rcu_assign_pointer(hbucket(t, key), NULL);
kfree_rcu(n, rcu);