Re: [musl] Re: Compiler support for erasure of sensitive data

[Denys Vlasenko <vda.linux@googlemail.com>]

On Wed, Sep 9, 2015 at 10:26 PM, Szabolcs Nagy <nsz@port70.net> wrote:
> * Zack Weinberg <zackw@panix.com> [2015-09-09 15:03:50 -0400]:
>> On 09/09/2015 02:02 PM, Paul_Koning@Dell.com wrote:
>> >> On Sep 9, 2015, at 1:54 PM, David Edelsohn <dje.gcc@gmail.com>
>> >> wrote:
>> >>
>> >> What level of erasure of sensitive data are you trying to ensure?
>> >> Assuming that overwriting values in the ISA registers actually
>> >> completely clears and destroys the values is delusionally naive.
>> >
>> > Could you point to some references about that?
>>
>> I *assume* David is referring to register renaming, which is not
>> architecturally visible...
>>
>
> or async signal handler copying all the register state on sigaltstack
> or internal counters and debug features making sensitive info observable
> or timing/cache-effect side channels that let other processes get info
> or compiling to a highlevel language (js) with different kind of leaks
> or running under emulator/debugger that can make secrets visible
> or...

I think if attacker got that much control of the machine that he can
get, for example, signals to reach your sensitive process, you already lost.
Ditto for running under emulator.