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().
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 <segoon@openwall.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Vasiliy Kulikov 2011-03-20 15:42:52 +01:00 committed by Patrick McHardy
parent db856674ac
commit 961ed183a9

View File

@ -664,8 +664,11 @@ 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);