On Wed, 8 Apr 2009 21:39:26 -0300 Jorge Morais <please.no.spam.h...@gmail.com> wrote:
> From the info page of GCC 4.3.3 > NOTE: In Gentoo, `-D_FORTIFY_SOURCE=2' is set by default, and is > activated when `-O' is set to 2 or higher. This enables > additional compile-time and run-time checks for several libc > functions. To disable, specify either `-U_FORTIFY_SOURCE' or > `-D_FORTIFY_SOURCE=0'. > > I have seen some FORTIFY_SOURCE bugs in the bugzilla and in some > cases, people claim the the bug lies in the FORTIFY_SOURCE feature > itself (that is, people claim that FORTIFY_SOURCE misidentifies a > buffer overflow). One example: > http://bugs.gentoo.org/show_bug.cgi?id=257016 Very rare, but it happens. > I have installed GCC-4.3.3 (but have not enabled it through > gcc-config yet), but my system is otherwise mostly stable. > > 1) I would like to use GCC-4.3.3 because it is the latest bugfix > release and is presumably more bug-free (correct?). So far, yes. Especially users of -march=amdfam10 flag want this version. > 2) But until FORTIFY_SOURCE is stable on Gentoo, I don't want it. > How can I disable it? CXXFLAGS="-U_FORTIFY_SOURCE" That's where most ebuilds will pick it up. > If I add -U_FORTIFY_SOURCE to CPPFLAGS (this would be the correct > place to add it, right?), wouldn't it disable the feature for every > package, even for those that specify FORTIFY_SOURCE on their own? Yes, but in general, packages have not been specifying _FORTIFY_SOURCE. It's a new feature in recent glibcs that was only made usable in glibc-2.8. > I want the traditional behavior: packages that ask for FORTIFY_SOURCE > get it, those that don't ask don't get it. Packages don't ask for FORTIFY_SOURCE. They get it, good and hard. FORTIFY_SOURCE is a one-time pain for longterm gain. > And of course, do you know if FORTIFY_SOURECE has a significant > performance cost and if it is really ready to be default (as in, > it is unlikely for new false positives to appear)? It has virtually no performance cost. > Also, am I wise to use GCC 4.3.3 compiler in a mostly stable system? At the moment, we are only processing bugs about _FORTIFY_SOURCE when they can be confirmed on ~arch. As long as you're prepared to use package.keywords liberally, it should be mostly ok. /loki_val
