Re: Question: a module for wiping userspace RAM before shutdown/reboot/halt

[David Hildenbrand <david@redhat.com>]

On 19.05.25 09:26, Danill Klimuk wrote:
> Hi Christophe, thank you for the answer.
> 
>   > What do you mean by 'wiping', do you mean 'clearing' ?
> 
> Yes, by 'wiping' I mean 'clearing'.
> 
>   > Can you explain the reason this is needed?
> 
> Some of our clients want to clear user space RAM during
> shutdown/reboot/halt sequences of Linux kernel, so the process data or
> any other leftovers do not leak outside current Linux kernel session
> (that is to firmware, or the next boot software, etc.). The reason for
> it to be a module that will execute in a specific moment of the
> sequences is to make it more predictable.
> 
> I thought that if the clients want to use it, maybe it will be useful
> for others too :).

We do have the init_on_free=1 boot option, whereby any pages freed back 
to the page allocator will get immediately zeroed.

This also makes sure that if you quit a process and then 
shutdown/reboot, that the page content was already cleared. (otherwise, 
it would simply be free memory in the allocator and no longer "userspace 
RAM")

-- 
Cheers,

David / dhildenb