From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Tue, 21 Jun 2022 12:01:41 +0000 (+0200)
Subject: netfilter: nft_dynset: restore set element counter when failing to update
X-Git-Tag: v5.15.73~2656
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=031561caa38a67cbf3084c38b8ebed52bbc1e602;p=platform%2Fkernel%2Flinux-rpi.git

netfilter: nft_dynset: restore set element counter when failing to update

commit 05907f10e235680cc7fb196810e4ad3215d5e648 upstream.

This patch fixes a race condition.

nft_rhash_update() might fail for two reasons:

- Element already exists in the hashtable.
- Another packet won race to insert an entry in the hashtable.

In both cases, new() has already bumped the counter via atomic_add_unless(),
therefore, decrement the set element counter.

Fixes: 22fe54d5fefc ("netfilter: nf_tables: add support for dynamic set updates")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c
index df40314d..76de6c8 100644
--- a/net/netfilter/nft_set_hash.c
+++ b/net/netfilter/nft_set_hash.c
@@ -143,6 +143,7 @@ static bool nft_rhash_update(struct nft_set *set, const u32 *key,
 	/* Another cpu may race to insert the element with the same key */
 	if (prev) {
 		nft_set_elem_destroy(set, he, true);
+		atomic_dec(&set->nelems);
 		he = prev;
 	}
 
@@ -152,6 +153,7 @@ out:
 
 err2:
 	nft_set_elem_destroy(set, he, true);
+	atomic_dec(&set->nelems);
 err1:
 	return false;
 }