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 X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8309AC169C4 for ; Sun, 3 Feb 2019 14:20:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5CFA52084A for ; Sun, 3 Feb 2019 14:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729882AbfBCOUV (ORCPT ); Sun, 3 Feb 2019 09:20:21 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55348 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729782AbfBCOUS (ORCPT ); Sun, 3 Feb 2019 09:20:18 -0500 Received: from cable-78.29.236.164.coditel.net ([78.29.236.164] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gqId6-0006G7-NT; Sun, 03 Feb 2019 14:20:16 +0000 Received: from ben by deadeye with local (Exim 4.92-RC4) (envelope-from ) id 1gqI9U-0006qG-Pe; Sun, 03 Feb 2019 14:49:40 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Simon Veith" , "David Woodhouse" , "Stefan Nuernberger" , "David S. Miller" , "Paul Moore" Date: Sun, 03 Feb 2019 14:45:08 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 039/305] net/ipv4: defensive cipso option parsing In-Reply-To: X-SA-Exim-Connect-IP: 78.29.236.164 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.63-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Stefan Nuernberger commit 076ed3da0c9b2f88d9157dbe7044a45641ae369e upstream. commit 40413955ee26 ("Cipso: cipso_v4_optptr enter infinite loop") fixed a possible infinite loop in the IP option parsing of CIPSO. The fix assumes that ip_options_compile filtered out all zero length options and that no other one-byte options beside IPOPT_END and IPOPT_NOOP exist. While this assumption currently holds true, add explicit checks for zero length and invalid length options to be safe for the future. Even though ip_options_compile should have validated the options, the introduction of new one-byte options can still confuse this code without the additional checks. Signed-off-by: Stefan Nuernberger Cc: David Woodhouse Cc: Simon Veith Acked-by: Paul Moore Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv4/cipso_ipv4.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) --- a/net/ipv4/cipso_ipv4.c +++ b/net/ipv4/cipso_ipv4.c @@ -1595,7 +1595,7 @@ static int cipso_v4_parsetag_loc(const s * * Description: * Parse the packet's IP header looking for a CIPSO option. Returns a pointer - * to the start of the CIPSO option on success, NULL if one if not found. + * to the start of the CIPSO option on success, NULL if one is not found. * */ unsigned char *cipso_v4_optptr(const struct sk_buff *skb) @@ -1605,10 +1605,8 @@ unsigned char *cipso_v4_optptr(const str int optlen; int taglen; - for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 0; ) { + for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 1; ) { switch (optptr[0]) { - case IPOPT_CIPSO: - return optptr; case IPOPT_END: return NULL; case IPOPT_NOOP: @@ -1617,6 +1615,11 @@ unsigned char *cipso_v4_optptr(const str default: taglen = optptr[1]; } + if (!taglen || taglen > optlen) + return NULL; + if (optptr[0] == IPOPT_CIPSO) + return optptr; + optlen -= taglen; optptr += taglen; }