[PATCH AUTOSEL 5.4 25/58] netfilter: ipset: Fix forceadd evaluation path

[Sasha Levin]

From: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx>

[ Upstream commit 8af1c6fbd9239877998c7f5a591cb2c88d41fb66 ]

When the forceadd option is enabled, the hash:* types should find and replace
the first entry in the bucket with the new one if there are no reuseable
(deleted or timed out) entries. However, the position index was just not set
to zero and remained the invalid -1 if there were no reuseable entries.

Reported-by: syzbot+6a86565c74ebe30aea18@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 23c42a403a9c ("netfilter: ipset: Introduction of new commands and protocol version 7")
Signed-off-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/netfilter/ipset/ip_set_hash_gen.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 2ac28c5c7e957..2389c9f89e481 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -931,6 +931,8 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
 		}
 	}
 	if (reuse || forceadd) {
+		if (j == -1)
+			j = 0;
 		data = ahash_data(n, j, set->dsize);
 		if (!deleted) {
 #ifdef IP_SET_HASH_WITH_NETS
-- 
2.20.1