On 25 April 2014 22:38, Chad Perrin <c...@apotheon.net> wrote: > On Fri, Apr 25, 2014 at 09:52:25PM +0100, Ben Laurie wrote: >> On 25 April 2014 21:46, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: >> > In message >> > <CAG5KPzw_cOfFLX_kn=5dwax+z+9vexuzo3q8yekdjg37tdq...@mail.gmail.com> >> > , Ben Laurie writes: >> >>On 25 April 2014 21:24, Ronald F. Guilmette <r...@tristatelogic.com> wrote: >> >>> Separately, a code example of the following general form was discussed: >> >>> >> >>> if (condition) variable = value1; >> >>> if (!condition) variable = value2; >> >>> use (variable); >> >>> >> > >> >>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. >> > >> > The way you do that *IS* to assert that the variable is indeed >> > set to something you can use. >> >> That only works if there's at least one illegal value, though. And you >> know what it is :-) > > With the proposed initialization value of -1, you could at least assert > that it is no longer -1, which at least indicates you have done > *something* to it in your code -- which, I believe, solves the problem > the code analyzer actually "intended" to point out, which is that it > might be possible for a variable to be used without any value assigned > to it (thus potentially reading garbage from a variable).
Only if -1 cannot be either value1 or value2, that's my point. > > >> > >> > If your "security" source code does not have at least 10% assert >> > lines, you're not really serious about security. >> >> People get really pissed off when I put asserts into OpenSSL. >> >> Perhaps they'll have a different opinion now. > > . . . or maybe we'll all end up using LibreSSL in the not-to-distant > future and it will not matter any longer (for some definition of "we" > that does not include banks running "secure" software on VMS past its > epoch). Or Windows or Linux or ... > > -- > Chad Perrin [ original content licensed OWL: http://owl.apotheon.org ] > _______________________________________________ > freebsd-security@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscr...@freebsd.org" _______________________________________________ freebsd-security@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "freebsd-security-unsubscr...@freebsd.org"
