From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 351C7C433EF for ; Wed, 22 Jun 2022 09:32:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350122AbiFVJca (ORCPT ); Wed, 22 Jun 2022 05:32:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235193AbiFVJca (ORCPT ); Wed, 22 Jun 2022 05:32:30 -0400 Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 49C463878C for ; Wed, 22 Jun 2022 02:32:29 -0700 (PDT) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Subject: [PATCH nf] netfilter: nft_dynset: restore set element counter when failing to update Date: Wed, 22 Jun 2022 11:32:19 +0200 Message-Id: <20220622093219.194566-1-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org 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(). Decrement the set element counter in this case. Fixes: 22fe54d5fefc ("netfilter: nf_tables: add support for dynamic set updates") Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_set_hash.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/netfilter/nft_set_hash.c b/net/netfilter/nft_set_hash.c index df40314de21f..23a5cfbe3855 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; } @@ -151,6 +152,7 @@ static bool nft_rhash_update(struct nft_set *set, const u32 *key, return true; err2: + atomic_dec(&set->nelems); nft_set_elem_destroy(set, he, true); err1: return false; -- 2.30.2