[media] siano: make it work again with CONFIG_VMAP_STACK

Reported as a Kaffeine bug:
	https://bugs.kde.org/show_bug.cgi?id=375811

The USB control messages require DMA to work. We cannot pass
a stack-allocated buffer, as it is not warranted that the
stack would be into a DMA enabled area.

On Kernel 4.9, the default is to not accept DMA on stack anymore
on x86 architecture. On other architectures, this has been a
requirement since Kernel 2.2. So, after this patch, this driver
should likely work fine on all archs.

Tested with USB ID 2040:5510: Hauppauge Windham

Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/usb/siano/smsusb.c b/drivers/media/usb/siano/smsusb.c
index a4dcaec..8c1f926 100644 (file)
--- a/drivers/media/usb/siano/smsusb.c
+++ b/drivers/media/usb/siano/smsusb.c
@@ -218,22 +218,30 @@ static int smsusb_start_streaming(struct smsusb_device_t *dev)
 static int smsusb_sendrequest(void *context, void *buffer, size_t size)
 {
        struct smsusb_device_t *dev = (struct smsusb_device_t *) context;
-       struct sms_msg_hdr *phdr = (struct sms_msg_hdr *) buffer;
-       int dummy;
+       struct sms_msg_hdr *phdr;
+       int dummy, ret;
 
        if (dev->state != SMSUSB_ACTIVE) {
                pr_debug("Device not active yet\n");
                return -ENOENT;
        }
 
+       phdr = kmalloc(size, GFP_KERNEL);
+       if (!phdr)
+               return -ENOMEM;
+       memcpy(phdr, buffer, size);
+
        pr_debug("sending %s(%d) size: %d\n",
                  smscore_translate_msg(phdr->msg_type), phdr->msg_type,
                  phdr->msg_length);
 
        smsendian_handle_tx_message((struct sms_msg_data *) phdr);
-       smsendian_handle_message_header((struct sms_msg_hdr *)buffer);
-       return usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 2),
-                           buffer, size, &dummy, 1000);
+       smsendian_handle_message_header((struct sms_msg_hdr *)phdr);
+       ret = usb_bulk_msg(dev->udev, usb_sndbulkpipe(dev->udev, 2),
+                           phdr, size, &dummy, 1000);
+
+       kfree(phdr);
+       return ret;
 }
 
 static char *smsusb1_fw_lkup[] = {