[Bug sanitizer/81715] asan-stack=1 redzone allocation is too inflexible

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81715

--- Comment #33 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Arnd Bergmann from comment #32)
> (In reply to Martin Liška from comment #31)
> > (In reply to Arnd Bergmann from comment #30)
> > > (In reply to Martin Liška from comment #29)
> > > > Which is very promising improvement I would say.
> > > 
> > > Agreed, this looks great. With most of the warnings against the
> > > 2048 byte limit gone, we can probably work around the remaining
> > > ones by doing local code changes in the kernel. I had patches for
> > > some of these in the past, which I can dig up then.
> > 
> > Just out of curiosity. Am I right that you're using KASAN build for
> > syzkaller or an other fuzzer? If so, I bet you can't hit most of the
> > stack overflows in drivers as you very probably don't have the
> > real hardware?
> 
> No, I don't do any fuzzing myself. The side project that I'm
> interested in here is to build the kernel in all random
> configurations without compile-time warnings that may indicate
> bugs. I tend to build several hundred such kernels per day to
> catch new bugs in both the (linux-next) kernel and in the
> toolchain (clang and gcc).

Ok, btw. it helped to expose multiple issues in ASAN implementation in GCC. So
then it's useful even though you're then not running the instrumented kernels.