From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 612494BA1F1; Wed, 16 Sep 2026 23:17:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789600625; cv=none; b=hxRPlFUJg7jCXVE8cUYv41UwupTc6xARUnkt+a+l2yYPqykWFjGGTbO1ygQGf33qbKkFzcgD1sT0GcVjeFe0HUz2iZ1h2yNOcyOxAfCvKHZGRaOP6abvmsWnEQHFdMnYx3WAVWsd2R6gki+LxNjNeC2P+30O30cq5LokR45XqWQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789600625; c=relaxed/simple; bh=/RQHfKgCaU147VxaqvEupAC0iifZR3I20zA7MLbwWlM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kxrgoHJdRusKLYGvcwC+R0FKySuik3goK5uxCquUSKEq2egjr77agey9pbU5n/36j8IBn3lNn12f2bTKMYoKNhuySuAA9seMlKAXAv4YaXpnTxfBE3jD/WTthtb5jACBEQDT6voeQqLL+dvvXiIvzj9SeQoS5pIsiT6CnMJaLEg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=oSm4oPSb; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="oSm4oPSb" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1789600622; bh=2AhBNRafA8j6ojIqlQWNUURFuw21/+BbcwdGr0mr26w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oSm4oPSb0VtX3VYD6Yno1jbQCXJqvtffd8qEal4lxsJlyvxAei8uZe9ADQA9ySDxW IaCTYSO4i6+kAibQIQDhSPaCwD1s+HdW8zlaAYC5NH9o63kWZZwBHYeJ25nnb7U+KL KeH9BkD1Y8NLtypbCI1LMPxTEhLyaS2WWjXsk0/RrvLSJAjWA4yGdQ10remagQiK0s cZ83AhYGGvVLv/f17LPfbBuAENt0xALZDglH/0SsYfd9t5q3FuCbwbGTaAOInZ6j6l i9q6KJxgs1Bkiyvh43lBJ8lEza9fnSbC6DSsi5s6qcJzFNnclkYMSXY1NcxybFRc6w gz8UaR2aPkXzw== Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 9AEEB60090; Thu, 17 Sep 2026 01:17:01 +0200 (CEST) From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, horms@kernel.org, fw@strlen.de, ja@ssi.bg Subject: [PATCH net 04/10] netfilter: ip6t_rt: fix zero-address non-strict match out-of-bounds read Date: Thu, 17 Sep 2026 01:16:45 +0200 Message-ID: <20260916231652.127456-5-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260916231652.127456-1-pablo@netfilter.org> References: <20260916231652.127456-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Luxiao Xu rt_mt6_check() permits rules to be configured with rtinfo->addrnr == 0 even when address matching (IP6T_RT_FST_MASK) is requested. In the IP6T_RT_FST_NSTRICT path, rt_mt6() evaluates packet routing addresses against rtinfo->addrs[i] and terminates backwards at the bottom of the loop: if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) { i++; } if (i == rtinfo->addrnr) break; When addrnr is 0, if the first packet address matches rtinfo->addrs[0], i is incremented to 1. Because i is now strictly greater than addrnr (0), the loop termination condition (i == rtinfo->addrnr) is bypassed and will never be satisfied. If a crafted IPv6 packet contains matching routing addresses, i will advance past IP6T_RT_HOPS (16). The subsequent call to ipv6_addr_equal() reads beyond struct ip6t_rt, triggering UBSAN/KASAN out-of-bounds warnings or kernel panics. Fix this by: 1. Rejecting rules in rt_mt6_check() where IP6T_RT_FST_MASK is set but rtinfo->addrnr is zero. 2. In rt_mt6(), moving the termination condition (i < rtinfo->addrnr) into the for-loop header condition and removing the backwards break at the end of the loop body. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reported-by: Vega Suggested-by: Florian Westphal Assisted-by: LLM Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Signed-off-by: Pablo Neira Ayuso --- net/ipv6/netfilter/ip6t_rt.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/net/ipv6/netfilter/ip6t_rt.c b/net/ipv6/netfilter/ip6t_rt.c index 8051425213dd..9880faf3cc7d 100644 --- a/net/ipv6/netfilter/ip6t_rt.c +++ b/net/ipv6/netfilter/ip6t_rt.c @@ -96,7 +96,8 @@ static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par) unsigned int i = 0; for (temp = 0; - temp < (unsigned int)((hdrlen - 8) / 16); + temp < (unsigned int)((hdrlen - 8) / 16) && + i < rtinfo->addrnr; temp++) { ap = skb_header_pointer(skb, ptr @@ -112,8 +113,6 @@ static bool rt_mt6(const struct sk_buff *skb, struct xt_action_param *par) if (ipv6_addr_equal(ap, &rtinfo->addrs[i])) i++; - if (i == rtinfo->addrnr) - break; } if (i == rtinfo->addrnr) return ret; @@ -162,6 +161,12 @@ static int rt_mt6_check(const struct xt_mtchk_param *par) pr_info_ratelimited("too many addresses specified\n"); return -EINVAL; } + + if ((rtinfo->flags & IP6T_RT_FST_MASK) && !rtinfo->addrnr) { + pr_info_ratelimited("address list match requested but addrnr is 0\n"); + return -EINVAL; + } + if ((rtinfo->flags & (IP6T_RT_RES | IP6T_RT_FST_MASK)) && (!(rtinfo->flags & IP6T_RT_TYP) || (rtinfo->rt_type != 0) || -- 2.47.3