linux-kernel - [PATCH] ipv4: netfilter: ipt_CLUSTERIP: fix buffer overflow

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Message-Id: <1299780740-32652-1-git-send-email-segoon@openwall.com>
Date:	Thu, 10 Mar 2011 21:12:19 +0300
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	linux-kernel@...r.kernel.org
Cc:	security@...nel.org, Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>,
	Alexey Kuznetsov <kuznet@....inr.ac.ru>,
	James Morris <jmorris@...ei.org>,
	Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
	netfilter-devel@...r.kernel.org, netfilter@...r.kernel.org,
	coreteam@...filter.org, netdev@...r.kernel.org
Subject: [PATCH] ipv4: netfilter: ipt_CLUSTERIP: fix buffer overflow

buffer string is copied from userspace.  It is not checked whether it is
zero terminated.  This may lead to overflow inside of simple_strtoul().

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 <segoon@...nwall.com>
---
 Compile tested.

 net/ipv4/netfilter/ipt_CLUSTERIP.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 403ca57..7aabf9a 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -666,6 +666,7 @@ static ssize_t clusterip_proc_write(struct file *file, const char __user *input,
 
 	if (copy_from_user(buffer, input, PROC_WRITELEN))
 		return -EFAULT;
+	buffer[sizeof(buffer)-1] = 0;
 
 	if (*buffer == '+') {
 		nodenum = simple_strtoul(buffer+1, NULL, 10);
-- 
1.7.0.4

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