Re: [kernel-hardening] [PATCH 09/38] usercopy: Mark kmalloc caches as usercopy caches

[Christian Borntraeger]

On 28.01.20 00:19, Kees Cook wrote:
> On Thu, Jan 23, 2020 at 09:14:20AM +0100, Jiri Slaby wrote:
>> On 14. 11. 19, 22:27, Kees Cook wrote:
>>> On Tue, Nov 12, 2019 at 01:21:54PM -0800, Kees Cook wrote:
>>>> How is iucv the only network protocol that has run into this? Do others
>>>> use a bounce buffer?
>>>
>>> Another solution would be to use a dedicated kmem cache (instead of the
>>> shared kmalloc dma one)?
>>
>> Has there been any conclusion to this thread yet? For the time being, we
>> disabled HARDENED_USERCOPY on s390...
>>
>> https://lore.kernel.org/kernel-hardening/9519edb7-456a-a2fa-659e-3e5a1ff89466@xxxxxxx/
> 
> I haven't heard anything new. What did people think of a separate kmem
> cache?
> 

Adding Julian and Ursula. A separate kmem cache for iucv might be indeed
a solution for the user hardening issue.
On the other hand not marking the DMA caches still seems questionable.

For reference
https://bugzilla.suse.com/show_bug.cgi?id=1156053
the kernel hardening now triggers a warning.