lkml.org 
[lkml]   [2018]   [Feb]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] KVM: SVM: Fix sparse: incorrect type in argument 1 (different base types)
From
Date
On 22/02/2018 16:56, Brijesh Singh wrote:
>
>
> On 02/21/2018 02:18 PM, Al Viro wrote:
>> On Wed, Feb 21, 2018 at 01:59:55PM -0600, Brijesh Singh wrote:
>>
>>> Sure, checking access_ok() does not guarantee that later
>>> copy_from_user() will not fail. But it does eliminate one possible
>>> reason for the failure. We are trying to validate most of the user
>>> inputs before we invoke  SEV command.
>>
>> That makes no sense whatsoever.  If user is deliberately fuzzing
>> your code or trying to DoS it, that "validation" doesn't buy you
>> anything - they can just as well feed you NULL, after all.
>>
>
>
> Currently, we let user query the blob length with params.len == 0 ||
> param.uaddr == NULL. We could limit it to just params.len == 0.
>
>
>> What is the rationale for that?  "Userland is accidentally feeding
>> us garbage pointers" is the case where slowness is the least of your
>> concerns...
>>
>
> My intent was to do some obvious failure checks on user inputs before
> invoking the HW. I do see your point that if userspace is feeding us
> garbage then slowness is least of our concern. If you think that we
> should not be using access_ok() in this particular case then I am okay
> with it.

Can you please send a patch? Thanks!

Paolo

\
 
 \ /
  Last update: 2018-02-23 19:06    [W:0.195 / U:0.412 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site