[media] v4l2-ioctl: add blocks check for VIDIOC_SUBDEV_G/S_EDID

The maximum size of an EDID is 32768 bytes, which is 32768 / 128 = 256 blocks.
Return -EINVAL if blocks > 256 to ensure that the memory allocation is sane.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/v4l2-core/v4l2-ioctl.c

@@ -2212,6 +2212,10 @@ static int check_array_args(unsigned int cmd, void *parg, size_t *array_size,
 		struct v4l2_subdev_edid *edid = parg;
 
 		if (edid->blocks) {
+			if (edid->blocks > 256) {
+				ret = -EINVAL;
+				break;
+			}
 			*user_ptr = (void __user *)edid->edid;
 			*kernel_ptr = (void *)&edid->edid;
 			*array_size = edid->blocks * 128;