From patchwork Mon Jul 23 15:31:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Pisati X-Patchwork-Id: 947839 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=lists.ubuntu.com (client-ip=91.189.94.19; helo=huckleberry.canonical.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=canonical.com Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 41Z5762tZjz9s1R; Tue, 24 Jul 2018 01:31:14 +1000 (AEST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.86_2) (envelope-from ) id 1fhcnh-0005SW-Jk; Mon, 23 Jul 2018 15:31:05 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:128) (Exim 4.86_2) (envelope-from ) id 1fhcng-0005S4-IM for kernel-team@lists.ubuntu.com; Mon, 23 Jul 2018 15:31:04 +0000 Received: from 1.general.ppisati.uk.vpn ([10.172.193.134] helo=canonical.com) by youngberry.canonical.com with esmtpsa (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1fhcng-0002mx-9H for kernel-team@lists.ubuntu.com; Mon, 23 Jul 2018 15:31:04 +0000 From: Paolo Pisati To: kernel-team@lists.ubuntu.com Subject: [PATCH] ip6_gre: fix ip6gre_err() invalid reads Date: Mon, 23 Jul 2018 17:31:03 +0200 Message-Id: <1532359863-18441-2-git-send-email-paolo.pisati@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1532359863-18441-1-git-send-email-paolo.pisati@canonical.com> References: <1532359863-18441-1-git-send-email-paolo.pisati@canonical.com> X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Eric Dumazet CVE-2017-5897 Andrey Konovalov reported out of bound accesses in ip6gre_err() If GRE flags contains GRE_KEY, the following expression *(((__be32 *)p) + (grehlen / 4) - 1) accesses data ~40 bytes after the expected point, since grehlen includes the size of IPv6 headers. Let's use a "struct gre_base_hdr *greh" pointer to make this code more readable. p[1] becomes greh->protocol. grhlen is the GRE header length. Fixes: c12b395a4664 ("gre: Support GRE over IPv6") Signed-off-by: Eric Dumazet Reported-by: Andrey Konovalov Signed-off-by: David S. Miller (cherry picked from commit 7892032cfe67f4bde6fc2ee967e45a8fbaf33756) Signed-off-by: Paolo Pisati Acked-by: Stefan Bader --- net/ipv6/ip6_gre.c | 41 ++++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c index 7075205..11feae0 100644 --- a/net/ipv6/ip6_gre.c +++ b/net/ipv6/ip6_gre.c @@ -56,6 +56,7 @@ #include #include +#include static bool log_ecn_error = true; module_param(log_ecn_error, bool, 0644); @@ -366,35 +367,37 @@ static void ip6gre_tunnel_uninit(struct net_device *dev) static void ip6gre_err(struct sk_buff *skb, struct inet6_skb_parm *opt, - u8 type, u8 code, int offset, __be32 info) + u8 type, u8 code, int offset, __be32 info) { - const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)skb->data; - __be16 *p = (__be16 *)(skb->data + offset); - int grehlen = offset + 4; + const struct gre_base_hdr *greh; + const struct ipv6hdr *ipv6h; + int grehlen = sizeof(*greh); struct ip6_tnl *t; + int key_off = 0; __be16 flags; + __be32 key; - flags = p[0]; - if (flags&(GRE_CSUM|GRE_KEY|GRE_SEQ|GRE_ROUTING|GRE_VERSION)) { - if (flags&(GRE_VERSION|GRE_ROUTING)) - return; - if (flags&GRE_KEY) { - grehlen += 4; - if (flags&GRE_CSUM) - grehlen += 4; - } + if (!pskb_may_pull(skb, offset + grehlen)) + return; + greh = (const struct gre_base_hdr *)(skb->data + offset); + flags = greh->flags; + if (flags & (GRE_VERSION | GRE_ROUTING)) + return; + if (flags & GRE_CSUM) + grehlen += 4; + if (flags & GRE_KEY) { + key_off = grehlen + offset; + grehlen += 4; } - /* If only 8 bytes returned, keyed message will be dropped here */ - if (!pskb_may_pull(skb, grehlen)) + if (!pskb_may_pull(skb, offset + grehlen)) return; ipv6h = (const struct ipv6hdr *)skb->data; - p = (__be16 *)(skb->data + offset); + greh = (const struct gre_base_hdr *)(skb->data + offset); + key = key_off ? *(__be32 *)(skb->data + key_off) : 0; t = ip6gre_tunnel_lookup(skb->dev, &ipv6h->daddr, &ipv6h->saddr, - flags & GRE_KEY ? - *(((__be32 *)p) + (grehlen / 4) - 1) : 0, - p[1]); + key, greh->protocol); if (t == NULL) return;