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 71B24EB64DD for ; Thu, 20 Jul 2023 19:29:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230177AbjGTT3U (ORCPT ); Thu, 20 Jul 2023 15:29:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229690AbjGTT3T (ORCPT ); Thu, 20 Jul 2023 15:29:19 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:237:300::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 43FDF171D for ; Thu, 20 Jul 2023 12:29:18 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1qMZKt-0002DK-R7; Thu, 20 Jul 2023 21:29:15 +0200 From: Florian Westphal To: Cc: Florian Westphal Subject: [PATCH net 1/5] netfilter: nf_tables: fix spurious set element insertion failure Date: Thu, 20 Jul 2023 21:29:07 +0200 Message-ID: <20230720192910.18125-1-fw@strlen.de> X-Mailer: git-send-email 2.41.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org On some platforms there is a padding hole in the nft_verdict structure, between the verdict code and the chain pointer. On element insertion, if the new element clashes with an existing one and NLM_F_EXCL flag isn't set, we want to ignore the -EEXIST error as long as the data associated with duplicated element is the same as the existing one. The data equality check uses memcmp. For normal data (NFT_DATA_VALUE) this works fine, but for NFT_DATA_VERDICT padding area leads to spurious failure even if the verdict data is the same. This then makes the insertion fail with 'already exists' error, even though the new "key : data" matches an existing entry and userspace told the kernel that it doesn't want to receive an error indication. Fixes: c016c7e45ddf ("netfilter: nf_tables: honor NLM_F_EXCL flag in set element insertion") Signed-off-by: Florian Westphal --- net/netfilter/nf_tables_api.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 237f739da3ca..79c7eee33dcd 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -10517,6 +10517,9 @@ static int nft_verdict_init(const struct nft_ctx *ctx, struct nft_data *data, if (!tb[NFTA_VERDICT_CODE]) return -EINVAL; + + /* zero padding hole for memcmp */ + memset(data, 0, sizeof(*data)); data->verdict.code = ntohl(nla_get_be32(tb[NFTA_VERDICT_CODE])); switch (data->verdict.code) { -- 2.41.0