Re: [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery

[Tony Luck]

On Fri, Aug 20, 2021 at 1:25 PM Luck, Tony <tony.luck@xxxxxxxxx> wrote:
> Probably the same for the two different addresses case ... though I'm
> not 100% confident about that. There could be some ioctl() that peeks
> at two parts of a passed in structure, and the user might pass in a
> structure that spans across a page boundary with both pages poisoned.
> But that would only hit if the driver code ignored the failure of the
> first get_user() and blindly tried the second. So I'd count that as a
> critically bad driver bug.

Or maybe driver writers are just evil :-(

for (i = 0; i < len; i++) {
       tx_wait(10);
       get_user(dsp56k_host_interface.data.b[1], bin++);
       get_user(dsp56k_host_interface.data.b[2], bin++);
       get_user(dsp56k_host_interface.data.b[3], bin++);
}

-Tony