On 08.12.22 08:28, Michael Adler wrote:
> Hi Jan,
> 
>> All that should be signed, so this is "just" a safety measure, right?
> 
> yes, this is just a convenience feature to give the user a proper error 
> message instead of (hundreds of thousands)
> synchronous exceptions.
> 
>> Is that enough, or should we look systematically for such things?
> 
> Well, I think this one was particularly "nasty" because it seems you will get 
> a synchronous exception for *every*
> invalid memory access (of which there are many due to the underflow). So I'd 
> say it's enough for the time being.
> However, I had to insert quite a few logging statements into the kernel stub 
> to find out what's going on. My custom
> kernel stub was quite verbose, which is probably not what you want by 
> default, but I'd fancy a mechanism to turn on
> verbose logging for the kernel stub (without having to recompile). I'm not 
> too familiar with UEFI programming, so
> I don't know how feasible that is.
> 

Rather than adding lots of runtime checks to the image, which is
specifically questionable in secure boot scenarios where the integrity
check comes first anyway, I wonder if we should rather improve the
generator script in this regard.

Jan

-- 
Siemens AG, Technology
Competence Center Embedded Linux

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