Messages in this thread | | | Subject | Re: [PATCH] KVM: SVM: Fix sparse: incorrect type in argument 1 (different base types) | From | Brijesh Singh <> | Date | Fri, 23 Feb 2018 12:26:40 -0600 |
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On 02/23/2018 12:05 PM, Paolo Bonzini wrote: > 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! >
Sure, I will send patch soon.
-Brijesh
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