[PATCH] lib: zlib: Use post-increment only in inffast.c

[Tan, Ley Foon]

> -----Original Message-----
> From: Tom Rini <trini at konsulko.com>
> Sent: Friday, October 16, 2020 8:37 PM
> To: Ley Foon Tan <lftan.linux at gmail.com>
> Cc: Tan, Ley Foon <ley.foon.tan at intel.com>; ZY - u-boot <u-
> boot at lists.denx.de>; See, Chin Liang <chin.liang.see at intel.com>
> Subject: Re: [PATCH] lib: zlib: Use post-increment only in inffast.c
> 
> On Fri, Oct 16, 2020 at 04:40:00AM +0800, Ley Foon Tan wrote:
> > On Fri, Jul 17, 2020 at 9:29 PM Tom Rini <trini at konsulko.com> wrote:
> > >
> > > On Wed, Jun 24, 2020 at 04:34:03PM +0800, Ley Foon Tan wrote:
> > >
> > > > From: Chin Liang See <chin.liang.see at intel.com>
> > > >
> > > > This fixes CVE-2016-9841. Changes integrated from [1], with
> > > > changes make for Uboot code base.
> > > >
> > > > An old inffast.c optimization turns out to not be optimal anymore
> > > > with modern compilers, and furthermore was not compliant with the
> > > > C standard, for which decrementing a pointer before its allocated
> > > > memory is undefined. Per the recommendation of a security audit of
> > > > the zlib code by Trail of Bits and TrustInSoft, in support of the
> > > > Mozilla Foundation, this "optimization" was removed, in order to
> > > > avoid the possibility of undefined behavior.
> > > >
> > > > [1]:
> > > >
> https://github.com/madler/zlib/commit/9aaec95e82117c1cb0f9624264c3
> > > > 618fc380cecb
> > > >
> > > > Signed-off-by: Mark Adler <madler at alumni.caltech.edu>
> > > > Signed-off-by: Chin Liang See <chin.liang.see at intel.com>
> > > > Signed-off-by: Ley Foon Tan <ley.foon.tan at intel.com>
> > >
> > > This breaks the following tests on sandbox:
> > > FAILED test/py/tests/test_efi_fit.py::test_efi_fit_launch -
> > > u_boot_spawn.Timeout FAILED test/py/tests/test_fit.py::test_fit -
> > > OSError: [Errno 5] Input/output error
> > >
> > Hi Tom
> >
> > I have tried to run the sandtest, but it failed in different test
> > cases. I am run this command "./test/py/test.py --bd sandbox --build".
> > Error log at bottom of email.
> >
> > Found that
> > https://gitlab.denx.de/u-boot/u-boot/-/blob/master/lib/zlib/zlib.h
> > always "#undef POSTINC", it is mean that U-boot can only support
> > pre-increment? I have tried changing "#undef POSTINC" to "define
> > POSTINC" and without this patch, the test failed at the same location.
> > So, the failure is not caused by this patch.
> > Note, this patch mainly changes to support post-increment only.
> >
> > Any suggestion to fix this?
> 
> I'm not sure why the tests fail for you to start with.  They all pass inn the CI
> environment as well as locally.  I would start by seeing how your
> environment differs from those.

Hi Tom

My test is running on Ubuntu 20.04 Linux.

Can you try change "#undef POSTINC" to "#define POSTINC" in lib/zlib/zlib.h if you can see the error?

Regards
Ley Foon