From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [91.216.245.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A8293A1A4D; Wed, 8 Apr 2026 16:35:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.216.245.30 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775666131; cv=none; b=Egz3sJ1B1Yx117fYvgP5aYoIUOBs8LMmCKykbZZrFXmgbn0nUYhX2w9YQN+ftBefOR+kUhLvHTEalNGDzDIm8o65ssOTfkxSZgFsIYe25O4P7zax0swBuxV3Wu74DxuvlniSsYT/I4yOik1Cl4UL+3g+d8q5Gf5k+b/LPOPJd9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775666131; c=relaxed/simple; bh=SjMNDw3SfdzJVLoRRDNS82BHpA3RIY3BkTvJxwqHNiw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ks18xNQBdKC6NKyvX525fUK10gkHFvV0OMy2zqawZwSNinW5bMV5g7r3CYA6WqXIsIO+tfYd8Sllt/ncAtOUgdO0ktZE3Y4ZxoIxMesY4cjTgf+NC3gqG3wyPNQqES6PeaZ9BGIqRfxYOBXII9ye1um12/9GTvwZvLhGBYPti8A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc; arc=none smtp.client-ip=91.216.245.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=strlen.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc Received: by Chamillionaire.breakpoint.cc (Postfix, from userid 1003) id 4BE9360560; Wed, 08 Apr 2026 18:35:28 +0200 (CEST) From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , pablo@netfilter.org Subject: [PATCH net 3/7] netfilter: xt_multiport: validate range encoding in checkentry Date: Wed, 8 Apr 2026 18:35:08 +0200 Message-ID: <20260408163512.30537-4-fw@strlen.de> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260408163512.30537-1-fw@strlen.de> References: <20260408163512.30537-1-fw@strlen.de> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Ren Wei ports_match_v1() treats any non-zero pflags entry as the start of a port range and unconditionally consumes the next ports[] element as the range end. The checkentry path currently validates protocol, flags and count, but it does not validate the range encoding itself. As a result, malformed rules can mark the last slot as a range start or place two range starts back to back, leaving ports_match_v1() to step past the last valid ports[] element while interpreting the rule. Reject malformed multiport v1 rules in checkentry by validating that each range start has a following element and that the following element is not itself marked as another range start. Fixes: a89ecb6a2ef7 ("[NETFILTER]: x_tables: unify IPv4/IPv6 multiport match") Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Yuhang Zheng Signed-off-by: Ren Wei Signed-off-by: Florian Westphal --- net/netfilter/xt_multiport.c | 34 ++++++++++++++++++++++++++++++---- 1 file changed, 30 insertions(+), 4 deletions(-) diff --git a/net/netfilter/xt_multiport.c b/net/netfilter/xt_multiport.c index 44a00f5acde8..a1691ff405d3 100644 --- a/net/netfilter/xt_multiport.c +++ b/net/netfilter/xt_multiport.c @@ -105,6 +105,28 @@ multiport_mt(const struct sk_buff *skb, struct xt_action_param *par) return ports_match_v1(multiinfo, ntohs(pptr[0]), ntohs(pptr[1])); } +static bool +multiport_valid_ranges(const struct xt_multiport_v1 *multiinfo) +{ + unsigned int i; + + for (i = 0; i < multiinfo->count; i++) { + if (!multiinfo->pflags[i]) + continue; + + if (++i >= multiinfo->count) + return false; + + if (multiinfo->pflags[i]) + return false; + + if (multiinfo->ports[i - 1] > multiinfo->ports[i]) + return false; + } + + return true; +} + static inline bool check(u_int16_t proto, u_int8_t ip_invflags, @@ -127,8 +149,10 @@ static int multiport_mt_check(const struct xt_mtchk_param *par) const struct ipt_ip *ip = par->entryinfo; const struct xt_multiport_v1 *multiinfo = par->matchinfo; - return check(ip->proto, ip->invflags, multiinfo->flags, - multiinfo->count) ? 0 : -EINVAL; + if (!check(ip->proto, ip->invflags, multiinfo->flags, multiinfo->count)) + return -EINVAL; + + return multiport_valid_ranges(multiinfo) ? 0 : -EINVAL; } static int multiport_mt6_check(const struct xt_mtchk_param *par) @@ -136,8 +160,10 @@ static int multiport_mt6_check(const struct xt_mtchk_param *par) const struct ip6t_ip6 *ip = par->entryinfo; const struct xt_multiport_v1 *multiinfo = par->matchinfo; - return check(ip->proto, ip->invflags, multiinfo->flags, - multiinfo->count) ? 0 : -EINVAL; + if (!check(ip->proto, ip->invflags, multiinfo->flags, multiinfo->count)) + return -EINVAL; + + return multiport_valid_ranges(multiinfo) ? 0 : -EINVAL; } static struct xt_match multiport_mt_reg[] __read_mostly = { -- 2.52.0