media: atomisp: Ensure that USERPTR pointers are page aligned

The atomisp code needs USERPTR pointers to be page aligned,
otherwise bad things (scribbling over other parts of the
process' RAM) happen.

Add a check to ensure this and exit VIDIOC_QBUF calls with
unaligned pointers with -EINVAL.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/staging/media/atomisp/pci/atomisp_ioctl.c

@@ -1345,6 +1345,12 @@ static int atomisp_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 	 * address and reprograme out page table properly
 	 */
 	if (buf->memory == V4L2_MEMORY_USERPTR) {
+		if (offset_in_page(buf->m.userptr)) {
+			dev_err(isp->dev, "Error userptr is not page aligned.\n");
+			ret = -EINVAL;
+			goto error;
+		}
+
 		vb = pipe->capq.bufs[buf->index];
 		vm_mem = vb->priv;
 		if (!vm_mem) {