From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752825AbdH1JBL (ORCPT ); Mon, 28 Aug 2017 05:01:11 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33706 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752682AbdH1IKL (ORCPT ); Mon, 28 Aug 2017 04:10:11 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Mateusz Jurczyk , Pablo Neira Ayuso , Florian Westphal Subject: [PATCH 4.12 80/99] netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv Date: Mon, 28 Aug 2017 10:05:18 +0200 Message-Id: <20170828080459.445716975@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170828080455.968552605@linuxfoundation.org> References: <20170828080455.968552605@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 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mateusz Jurczyk commit f55ce7b024090a51382ccab2730b96e2f7b4e9cf upstream. Verify that the length of the socket buffer is sufficient to cover the nlmsghdr structure before accessing the nlh->nlmsg_len field for further input sanitization. If the client only supplies 1-3 bytes of data in sk_buff, then nlh->nlmsg_len remains partially uninitialized and contains leftover memory from the corresponding kernel allocation. Operating on such data may result in indeterminate evaluation of the nlmsg_len < NLMSG_HDRLEN expression. The bug was discovered by a runtime instrumentation designed to detect use of uninitialized memory in the kernel. The patch prevents this and other similar tools (e.g. KMSAN) from flagging this behavior in the future. Signed-off-by: Mateusz Jurczyk Signed-off-by: Pablo Neira Ayuso Cc: Florian Westphal Signed-off-by: Greg Kroah-Hartman --- net/netfilter/nfnetlink.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -463,8 +463,7 @@ static void nfnetlink_rcv_skb_batch(stru if (msglen > skb->len) msglen = skb->len; - if (nlh->nlmsg_len < NLMSG_HDRLEN || - skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) + if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg)) return; err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy, @@ -491,7 +490,8 @@ static void nfnetlink_rcv(struct sk_buff { struct nlmsghdr *nlh = nlmsg_hdr(skb); - if (nlh->nlmsg_len < NLMSG_HDRLEN || + if (skb->len < NLMSG_HDRLEN || + nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len) return;