OpenSSL static analysis, was: De Raadt + FBSD + OpenSSH + hole?

[Chad Perrin]

On Fri, Apr 25, 2014 at 02:21:47PM -0700, Ronald F. Guilmette wrote:
> 
> In message <CAG5KPzw_cOfFLX_kn=5DWAX+z+9VeXuzo3Q8YekDJG37tDQ_wQ at mail.gmail.com>
> Ben Laurie <benl at freebsd.org> wrote:
> 
> >But that would then hide the error condition of it being not set to a
> >new value after initialisation.
> 
> The (modified/quieted) code example under discussion is as follows:
> 
> 	variable = value0;  /* initialization */
> 	if (condition) variable = value1;
> 	if (!condition) variable = value2;
> 	use (variable);
> 
> Please note that variable *is* *always* set to some value (either value1
> or value2) after initialization.  The "error condition" that you seem
> concerned about having explicitly flagged does not in fact exist in the
> example code snippet under discussion.
> 
> >One better answer would be to have a way to annotate that after the
> >two conditionals you assert that |variable| is initialised. Then a
> >future, smarter static analyzer can attempt to prove you wrong.
> 
> Sir, is there any sense in which the final line of the above example
> _does not_ already and standing all by itself constitute an implicit
> assertion that "variable" has been initialized by that point in the
> code?

I do believe you are right . . . at least until the code needs to be
edited for some reason.

-- 
Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ]