media: platform: davinci: return -EINVAL for VPFE_CMD_S_CCDC_RAW_PARAMS ioctl

this patch makes sure VPFE_CMD_S_CCDC_RAW_PARAMS ioctl no longer works
for vpfe_capture driver with a minimal patch suitable for backporting.

- This ioctl was never in public api and was only defined in kernel header.
- The function set_params constantly mixes up pointers and phys_addr_t
numbers.
- This is part of a 'VPFE_CMD_S_CCDC_RAW_PARAMS' ioctl command that is
described as an 'experimental ioctl that will change in future kernels'.
- The code to allocate the table never gets called after we copy_from_user
the user input over the kernel settings, and then compare them
for inequality.
- We then go on to use an address provided by user space as both the
__user pointer for input and pass it through phys_to_virt to come up
with a kernel pointer to copy the data to. This looks like a trivially
exploitable root hole.

Due to these reasons we make sure this ioctl now returns -EINVAL and backport
this patch as far as possible.

Fixes: 5f15fbb68fd7 ("V4L/DVB (12251): v4l: dm644x ccdc module for vpfe capture driver")

Signed-off-by: Lad, Prabhakar <[e-mail]>
Cc: <[e-mail]> # for v3.7 and up
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/platform/davinci/vpfe_capture.c

···
 
 	switch (cmd) {
 	case VPFE_CMD_S_CCDC_RAW_PARAMS:
+		ret = -EINVAL;
 		v4l2_warn(&vpfe_dev->v4l2_dev,
-			  "VPFE_CMD_S_CCDC_RAW_PARAMS: experimental ioctl\n");
-		if (ccdc_dev->hw_ops.set_params) {
-			ret = ccdc_dev->hw_ops.set_params(param);
-			if (ret) {
-				v4l2_dbg(1, debug, &vpfe_dev->v4l2_dev,
-					"Error setting parameters in CCDC\n");
-				goto unlock_out;
-			}
-			ret = vpfe_get_ccdc_image_format(vpfe_dev,
-							 &vpfe_dev->fmt);
-			if (ret < 0) {
-				v4l2_dbg(1, debug, &vpfe_dev->v4l2_dev,
-					"Invalid image format at CCDC\n");
-				goto unlock_out;
-			}
-		} else {
-			ret = -EINVAL;
-			v4l2_dbg(1, debug, &vpfe_dev->v4l2_dev,
-				"VPFE_CMD_S_CCDC_RAW_PARAMS not supported\n");
-		}
+			"VPFE_CMD_S_CCDC_RAW_PARAMS not supported\n");
 		break;
 	default:
 		ret = -ENOTTY;