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

[Tom Rini]

On Wed, Oct 21, 2020 at 03:42:10AM +0000, Tan, Ley Foon wrote:
> 
> 
> > -----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?

I see:
FAILED test/py/tests/test_efi_fit.py::test_efi_fit_launch - assert
'Hello, world' in "## Loa...
FAILED test/py/tests/test_fit.py::test_fit - OSError: [Errno 5]
Input/output error

as new problems with that change.

-- 
Tom
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