Bluetooth: Fix leak of uninitialized data to userspace

    struct hci_dev_list_req {
            __u16  dev_num;
            struct hci_dev_req dev_req[0];  /* hci_dev_req structures */
    };

sizeof(struct hci_dev_list_req) == 4, so the two bytes immediately
following "dev_num" will never be initialized. When this structure
is copied to userspace, these uninitialized bytes are leaked.

Fix by using kzalloc() instead of kmalloc(). Found using kmemcheck.
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_core.c

@@ -756,7 +756,7 @@ int hci_get_dev_list(void __user *arg)
 
 	size = sizeof(*dl) + dev_num * sizeof(*dr);
 
-	if (!(dl = kmalloc(size, GFP_KERNEL)))
+	if (!(dl = kzalloc(size, GFP_KERNEL)))
 		return -ENOMEM;
 
 	dr = dl->dev_req;