Code: static ssize_t lbs_debugfs_write(struct file *f, const char __user *buf,
			    size_t cnt, loff_t *ppos)
{
	int r, i;
	char *pdata;
	char *p;
	char *p0;
	char *p1;
 	char *p2;
 	struct debug_data *d = f->private_data;
 
	pdata = kmalloc(cnt, GFP_KERNEL);
 	if (pdata == NULL)
 		return 0;
 
	if (copy_from_user(pdata, buf, cnt)) {
		lbs_deb_debugfs("Copy from user failed\n");
 		kfree(pdata);
 		return 0;
 	}
 
 	p0 = pdata;
 	for (i = 0; i < num_of_items; i++) {
		do {
			p = strstr(p0, d[i].name);
			if (p == NULL)
				break;
			p1 = strchr(p, '\n');
			if (p1 == NULL)
				break;
			p0 = p1++;
			p2 = strchr(p, '=');
			if (!p2)
				break;
			p2++;
			r = simple_strtoul(p2, NULL, 0);
			if (d[i].size == 1)
				*((u8 *) d[i].addr) = (u8) r;
			else if (d[i].size == 2)
				*((u16 *) d[i].addr) = (u16) r;
			else if (d[i].size == 4)
				*((u32 *) d[i].addr) = (u32) r;
			else if (d[i].size == 8)
				*((u64 *) d[i].addr) = (u64) r;
			break;
		} while (1);
	}
	kfree(pdata);

	return (ssize_t)cnt;
}

Vulnerability Type: DoS 
CWE ID: CWE-189
Summary: The lbs_debugfs_write function in drivers/net/wireless/libertas/debugfs.c in the Linux kernel through 3.12.1 allows local users to cause a denial of service (OOPS) by leveraging root privileges for a zero-length write operation.
Commit Message: libertas: potential oops in debugfs

If we do a zero size allocation then it will oops.  Also we can't be
sure the user passes us a NUL terminated string so I've added a
terminator.

This code can only be triggered by root.

Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>