[PATCH] ipv4: netfilter: ipt_CLUSTERIP: fix buffer overflow

[Vasiliy Kulikov <segoon@openwall.com>]

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@openwall.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