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 8D94E40F8D5; Mon, 9 Mar 2026 21:09:07 +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=1773090548; cv=none; b=d6pLFMY94OdraSQ6RCmTwDMDS0koIyxdfRngBQrhFPJ0IQVP/nVIMcTACRP+mOX7Pfv0+b88mvmYkSwRPrdbxzc12K8g9qDY2uyy8fy5cOIPaEYFuijrZ7MQTUAjESxb3bD0xQ0c0Z52vz78rYHJ0BlscYcRqr52P7dQEOol0M8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773090548; c=relaxed/simple; bh=fF83qomXqdgo3XJul711dwJi28JL3p4+AwCVeNrIoZY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XmjHZp4puSs20OiPVonXcfRJshI8zztpK1NUPNHi/4nUha8SqCEEsLRFRevos49eykYLL/cl80H0OWtGqicjR6IYpRrPYzwojEK4LFlfj4J02jRscFNqhD1eg9VLxlzaFI5hLAoBYA2YpXkCvD38+un2eR871IT7W39UIEcZba4= 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 240DF6047A; Mon, 09 Mar 2026 22:09:06 +0100 (CET) From: Florian Westphal To: Cc: Paolo Abeni , "David S. Miller" , Eric Dumazet , Jakub Kicinski , , pablo@netfilter.org Subject: [PATCH net 04/10] netfilter: x_tables: guard option walkers against 1-byte tail reads Date: Mon, 9 Mar 2026 22:08:39 +0100 Message-ID: <20260309210845.15657-5-fw@strlen.de> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260309210845.15657-1-fw@strlen.de> References: <20260309210845.15657-1-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: David Dull When the last byte of options is a non-single-byte option kind, walkers that advance with i += op[i + 1] ? : 1 can read op[i + 1] past the end of the option area. Add an explicit i == optlen - 1 check before dereferencing op[i + 1] in xt_tcpudp and xt_dccp option walkers. Fixes: 2e4e6a17af35 ("[NETFILTER] x_tables: Abstraction layer for {ip,ip6,arp}_tables") Signed-off-by: David Dull Signed-off-by: Florian Westphal --- net/netfilter/xt_dccp.c | 4 ++-- net/netfilter/xt_tcpudp.c | 6 ++++-- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/net/netfilter/xt_dccp.c b/net/netfilter/xt_dccp.c index e5a13ecbe67a..037ab93e25d0 100644 --- a/net/netfilter/xt_dccp.c +++ b/net/netfilter/xt_dccp.c @@ -62,10 +62,10 @@ dccp_find_option(u_int8_t option, return true; } - if (op[i] < 2) + if (op[i] < 2 || i == optlen - 1) i++; else - i += op[i+1]?:1; + i += op[i + 1] ? : 1; } spin_unlock_bh(&dccp_buflock); diff --git a/net/netfilter/xt_tcpudp.c b/net/netfilter/xt_tcpudp.c index e8991130a3de..f76cf18f1a24 100644 --- a/net/netfilter/xt_tcpudp.c +++ b/net/netfilter/xt_tcpudp.c @@ -59,8 +59,10 @@ tcp_find_option(u_int8_t option, for (i = 0; i < optlen; ) { if (op[i] == option) return !invert; - if (op[i] < 2) i++; - else i += op[i+1]?:1; + if (op[i] < 2 || i == optlen - 1) + i++; + else + i += op[i + 1] ? : 1; } return invert; -- 2.52.0