Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937174AbdCJMVu (ORCPT ); Fri, 10 Mar 2017 07:21:50 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:45238 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934239AbdCJMVs (ORCPT ); Fri, 10 Mar 2017 07:21:48 -0500 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, "David S. Miller" , "Eric Dumazet" Date: Fri, 10 Mar 2017 11:46:23 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 335/370] ipv6: dccp: fix out of bound access in dccp_v6_err() In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1879 Lines: 53 3.16.42-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 1aa9d1a0e7eefcc61696e147d123453fc0016005 ] dccp_v6_err() does not use pskb_may_pull() and might access garbage. We only need 4 bytes at the beginning of the DCCP header, like TCP, so the 8 bytes pulled in icmpv6_notify() are more than enough. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller [bwh: Backported to 3.16: use offsetof() + sizeof() instead of offsetofend()] Signed-off-by: Ben Hutchings --- net/dccp/ipv6.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) --- a/net/dccp/ipv6.c +++ b/net/dccp/ipv6.c @@ -83,7 +83,7 @@ static void dccp_v6_err(struct sk_buff * u8 type, u8 code, int offset, __be32 info) { const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data; - const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); + const struct dccp_hdr *dh; struct dccp_sock *dp; struct ipv6_pinfo *np; struct sock *sk; @@ -91,12 +91,13 @@ static void dccp_v6_err(struct sk_buff * __u64 seq; struct net *net = dev_net(skb->dev); - if (skb->len < offset + sizeof(*dh) || - skb->len < offset + __dccp_basic_hdr_len(dh)) { - ICMP6_INC_STATS_BH(net, __in6_dev_get(skb->dev), - ICMP6_MIB_INERRORS); - return; - } + /* Only need dccph_dport & dccph_sport which are the first + * 4 bytes in dccp header. + * Our caller (icmpv6_notify()) already pulled 8 bytes for us. + */ + BUILD_BUG_ON(offsetof(struct dccp_hdr, dccph_sport) + sizeof(dh->dccph_sport) > 8); + BUILD_BUG_ON(offsetof(struct dccp_hdr, dccph_dport) + sizeof(dh->dccph_dport) > 8); + dh = (struct dccp_hdr *)(skb->data + offset); sk = inet6_lookup(net, &dccp_hashinfo, &hdr->daddr, dh->dccph_dport,