staging: gdm724x: Fix DMA from stack

commit 7c3a063 upstream.

Stack allocated buffers cannot be used for DMA
on all architectures so allocate hci_packet buffer
using kmalloc.

Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amey Narkhede <ameynarkhede03@gmail.com>
Link: https://lore.kernel.org/r/20210211053819.34858-1-ameynarkhede03@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm724x/gdm_usb.c

@@ -56,20 +56,24 @@ static int gdm_usb_recv(void *priv_dev,
 
 static int request_mac_address(struct lte_udev *udev)
 {
-	u8 buf[16] = {0,};
-	struct hci_packet *hci = (struct hci_packet *)buf;
+	struct hci_packet *hci;
 	struct usb_device *usbdev = udev->usbdev;
 	int actual;
 	int ret = -1;
 
+	hci = kmalloc(struct_size(hci, data, 1), GFP_KERNEL);
+	if (!hci)
+		return -ENOMEM;
+
 	hci->cmd_evt = gdm_cpu_to_dev16(udev->gdm_ed, LTE_GET_INFORMATION);
 	hci->len = gdm_cpu_to_dev16(udev->gdm_ed, 1);
 	hci->data[0] = MAC_ADDRESS;
 
-	ret = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, 2), buf, 5,
+	ret = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, 2), hci, 5,
 			   &actual, 1000);
 
 	udev->request_mac_addr = 1;
+	kfree(hci);
 
 	return ret;
 }