configfs: Return -EFBIG from configfs_write_bin_file.

commit 42857cf5 upstream.

The check for writing more than cb_max_size bytes does not 'goto out' so
it is a no-op which allows users to vmalloc an arbitrary amount.

Fixes: 03607ace ("configfs: implement binary attributes")
Signed-off-by: Phil Turnbull <phil.turnbull@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/configfs/file.c

@@ -333,6 +333,7 @@ configfs_write_bin_file(struct file *file, const char __user *buf,
 		if (bin_attr->cb_max_size &&
 			*ppos + count > bin_attr->cb_max_size) {
 			len = -EFBIG;
+			goto out;
 		}
 
 		tbuf = vmalloc(*ppos + count);