Re: [PATCH v3 2/4] bus: fsl-mc: add fsl-mc userspace support

gregkh
2018-11-20T16:48:56Z

On Tue, Nov 20, 2018 at 03:39:45PM +0000, Ioana Ciornei wrote:
> +static int fsl_mc_uapi_send_command(unsigned long arg,
> + struct fsl_mc_io *mc_io)
> +{
> + struct fsl_mc_command mc_cmd;
> + int error;
> +
> + error = copy_from_user(&mc_cmd, (void __user *)arg, sizeof(mc_cmd));
> + if (error)
> + return -EFAULT;
> +
> + error = mc_send_command(mc_io, &mc_cmd);
> + if (error)
> + return error;
> +
> + error = copy_to_user((void __user *)arg, &mc_cmd, sizeof(mc_cmd));
> + if (error)
> + return -EFAULT;
> +
> + return 0;
> +}

I know you said that "the firmware will properly verify the command"
already, but given that I used to be a firmware developer a long time
ago, I can almost guarantee that this will cause problems in the future.

Want to make a friendly bet about this?

What is the odds that your firmware api/interface has been properly
fuzzed such that all possible combinations of bad commands will really
not do horrible things to the hardware/system?

Are you all willing to bet the system intregrity on this? If so, ok,
it's your systems :)

Personally, I think you need to add a "known whitelist" and do some sort
of sanity checking here.

thanks,

greg k-h