From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752975AbdHISaA (ORCPT ); Wed, 9 Aug 2017 14:30:00 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:57268 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752655AbdHISPX (ORCPT ); Wed, 9 Aug 2017 14:15:23 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sabrina Dubroca , Hannes Frederic Sowa , "David S. Miller" Subject: [PATCH 4.9 43/93] ipv6: avoid overflow of offset in ip6_find_1stfragopt Date: Wed, 9 Aug 2017 11:13:36 -0700 Message-Id: <20170809181337.404786187@linuxfoundation.org> X-Mailer: git-send-email 2.14.0 In-Reply-To: <20170809181335.658857427@linuxfoundation.org> References: <20170809181335.658857427@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sabrina Dubroca [ Upstream commit 6399f1fae4ec29fab5ec76070435555e256ca3a6 ] In some cases, offset can overflow and can cause an infinite loop in ip6_find_1stfragopt(). Make it unsigned int to prevent the overflow, and cap it at IPV6_MAXPLEN, since packets larger than that should be invalid. This problem has been here since before the beginning of git history. Signed-off-by: Sabrina Dubroca Acked-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/output_core.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/ipv6/output_core.c +++ b/net/ipv6/output_core.c @@ -78,7 +78,7 @@ EXPORT_SYMBOL(ipv6_select_ident); int ip6_find_1stfragopt(struct sk_buff *skb, u8 **nexthdr) { - u16 offset = sizeof(struct ipv6hdr); + unsigned int offset = sizeof(struct ipv6hdr); unsigned int packet_len = skb_tail_pointer(skb) - skb_network_header(skb); int found_rhdr = 0; @@ -86,6 +86,7 @@ int ip6_find_1stfragopt(struct sk_buff * while (offset <= packet_len) { struct ipv6_opt_hdr *exthdr; + unsigned int len; switch (**nexthdr) { @@ -111,7 +112,10 @@ int ip6_find_1stfragopt(struct sk_buff * exthdr = (struct ipv6_opt_hdr *)(skb_network_header(skb) + offset); - offset += ipv6_optlen(exthdr); + len = ipv6_optlen(exthdr); + if (len + offset >= IPV6_MAXPLEN) + return -EINVAL; + offset += len; *nexthdr = &exthdr->nexthdr; }