[llvm-dev] LTO, ifuncs, and lld

[Shawn Webb via llvm-dev]

Hey Peter,

Here you go!

https://hardenedbsd.org/~shawn/2018-11-28_reproduce-01.tar

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

Tor-ified Signal:    +1 443-546-8752
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On Wed, Nov 28, 2018 at 05:30:57PM -0800, Peter Collingbourne wrote:
> Hi Shawn,
> 
> Can you please create a reproducer tarball (using ld.lld --reproduce) so
> that we don't need to install HardenedBSD in order to reproduce?
> 
> Peter
> 
> On Wed, Nov 28, 2018 at 5:16 PM Shawn Webb via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> 
> > Hey LLVM folks,
> >
> > I've run into an interesting assertion. In one of HardenedBSD's
> > feature branches, we're working on integration llvm's Cross-DSO CFI
> > implementation. Using Cross-DSO CFI requires building libs with LTO,
> > which causes clang to emit LLVM IR intermediate object files rather
> > than ELF intermediate object files.
> >
> > I've found that with lld, attempting to link LLVM IR intermediate
> > object files hits an assert in lld. I've created a reproduction test
> > case in this tiny little repo: https://github.com/lattera/ifunc_repro
> >
> > The assertion I hit is detailed in the commit message of the initial
> > commit:
> >
> > https://github.com/lattera/ifunc_repro/commit/0be98f9e81a1c91e80b135da6bb8d073d7a0c6f7
> >
> > HardenedBSD's Cross-DSO CFI feature branch uses clang/llvm/lld 7.0.1.
> > I'm more than happy to test out patches to help address this issue.
> >
> > Please let me know if you have any questions, comments, or concerns.
> >
> > Thanks,
> >
> > --
> > Shawn Webb
> > Cofounder and Security Engineer
> > HardenedBSD
> >
> > Tor-ified Signal:    +1 443-546-8752
> > Tor+XMPP+OTR:        lattera at is.a.hacker.sx
> > GPG Key ID:          0x6A84658F52456EEE
> > GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
> 
> 
> -- 
> -- 
> Peter
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