On Tue, Apr 07, 2020 at 12:19:45PM +0200, Richard Biener via Gcc-patches wrote:
> On Fri, Apr 3, 2020 at 11:59 PM Ian Lance Taylor via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
> >
> > The split-stack code invokes mmap and munmap with a limited amount of
> > stack space. That is fine when the functions just make a system call,
> > but it's not fine when programs use LD_PRELOAD or linker tricks to add
> > hooks to mmap/munmap. Those hooks may use too much stack space,
> > leading to an obscure program crash.
> >
> > Avoid that at least on GNU/Linux by calling __mmap/__munmap instead.
> >
> > Bootstrapped and ran Go and split-stack tests on x86_64-pc-linux-gnu.
> > Committed to mainline.
>
> This causes references to GLIBC_PRIVATE exported symbols which is
> highly undesirable for system integrators (no ABI stability is guaranteed
> for those). I opened the regression PR94513 for this.
Yeah, GLIBC_PRIVATE symbols may only be used by glibc itself, not by
anything else.
I'd suggest to use syscall function instead (though, that can be interposed
too).
Jakub
