Re: binfmt_elf: use ELF_ET_DYN_BASE only for PIE breaks asan

[Daniel Micay <danielmicay@gmail.com>]

On Mon, 2017-08-07 at 12:40 -0700, Kostya Serebryany wrote:
> 
> 
> On Mon, Aug 7, 2017 at 12:34 PM, Kees Cook <keescook@google.com>
> wrote:
> > (To be clear, this subthread is for dealing with _future_ changes;
> > I'm
> > already preparing the revert, which is in the other subthread.)
> > 
> > On Mon, Aug 7, 2017 at 12:26 PM, Kostya Serebryany <kcc@google.com>
> > wrote:
> > > Oh, a launcher (e.g. just using setarch) would be a huge pain to
> > deploy.
> > 
> > Would loading the executable into the mmap region work? 
> 
> This is beyond my knowledge. :( 
> Could you explain? 
> 
> If we can do this w/o a launcher (and w/o re-executing), we should
> try. 

If you launch a program with /usr/lib/ld-2.25.so /usr/bin/foo right now,
that probably already works because it disables the separate base.

There's probably a way to get ASan linked executables to disable the
separate PIE base automatically, making the exe get mapped with other
mmap allocations / libraries. I think that's the best approach.

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