From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vasiliy Kulikov Subject: [PATCH v2] ipv4: netfilter: ipt_CLUSTERIP: fix buffer overflow Date: Thu, 17 Mar 2011 14:32:29 +0300 Message-ID: <20110317113229.GA7710@albatros> References: <1299780740-32652-1-git-send-email-segoon@openwall.com> <4D7F5CAC.6070006@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Changli Gao , linux-kernel@vger.kernel.org, security@kernel.org, "David S. Miller" , Alexey Kuznetsov , James Morris , Hideaki YOSHIFUJI , netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org To: Patrick McHardy Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:63897 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753763Ab1CQLcf (ORCPT ); Thu, 17 Mar 2011 07:32:35 -0400 Content-Disposition: inline In-Reply-To: <4D7F5CAC.6070006@trash.net> Sender: netfilter-devel-owner@vger.kernel.org List-ID: 'buffer' string is copied from userspace. It is not checked whether it is zero terminated. This may lead to overflow inside of simple_strtoul(). Changli Gao suggested to copy not more than user supplied 'size' bytes. It was introduced before the git epoch. Files "ipt_CLUSTERIP/*" are root writable only by default, however, on some setups permissions might be relaxed to e.g. network admin user. Signed-off-by: Vasiliy Kulikov --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 1e26a48..af7dec6 100644 --- a/net/ipv4/netfilter/ipt_CLUSTERIP.c +++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c @@ -669,8 +669,11 @@ static ssize_t clusterip_proc_write(struct file *file, const char __user *input, char buffer[PROC_WRITELEN+1]; unsigned long nodenum; - if (copy_from_user(buffer, input, PROC_WRITELEN)) + if (size > PROC_WRITELEN) + return -EIO; + if (copy_from_user(buffer, input, size)) return -EFAULT; + buffer[size] = 0; if (*buffer == '+') { nodenum = simple_strtoul(buffer+1, NULL, 10); -- 1.7.0.4