Subject: Re: [PATCH] powerpc/pseries: Whitelist dtl slub object for copying to userspace

From: Kees Cook <[email-masked]>
Date: Thu, 20 Jun 2024 11:59:12 -0700

On Thu, Jun 20, 2024 at 10:58:49PM +0530, Anjali K wrote:
> However given that:                                                        
> (i) The dtl buffer is read-only. The dtl trace is a set of metrics which   
> are collected to be read by privileged users.                              
> (ii) Users usually reads all the dtl entries, not a subset.                                             
> (iii) Read overflows are unlikely to expose anything useful to attackers        
> since we are whitelisting the complete slub object and there are no        
> contiguous memory locations which need to be hidden.                       
> Can we go ahead with the whitelisting using kmem_cache_create_usercopy()   
> approach?                                                                  
> Or are there other reasons to prefer the bounce buffer approach?

Yeah, based on this and what mpe said, I have no objection to just
allowing it in kmem_cache_create_usercopy(). I was mainly just curious
what the threat model was. :)

Reviewed-by: Kees Cook <[email-masked]>

-- 
Kees Cook