[MODERATED] Re: LVI

On 19/11/19 19:12, speck for Greg KH wrote:
>> -#define __uaccess_begin_nospec()	\
>> +#define __uaccess_end_nospec()	\
>>  ({					\
>> -	stac();				\
>> +	clac();				\
>>  	barrier_nospec();		\
>>  })
> Um, don't we _really_ want stac() here?  That's the only thing that is
> saving our butts in a number of places.  Why get rid of it?  Otherwise
> it should be easy to cause a speculatave load by userspace for any
> address they feel like.
> 
> Or am I mistaken about what you are trying to solve here?

The diff is confusing, this is now an end-of-access macro
(__uaccess_begin_nospec got renamed to __uaccess_end_nospec) so you want
to re-enable SMAP here by clearing the AC flag.

Paolo