Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)

From	Kees Cook <keescook@chromium.org>
Newsgroups	linux.kernel
Subject	Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)
Date	2016-08-01 22:00 +0200
Message-ID	<s1rxv-2ia-23@gated-at.bofh.it> (permalink)
References	<rHxct-85W-11@gated-at.bofh.it> <rHxcu-85W-29@gated-at.bofh.it> <s1rxv-2ia-25@gated-at.bofh.it>
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On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
> Kees Cook <keescook@chromium.org> writes:
>
>> This adds a function that lives in the .rodata section. The section
>> flags are corrected using objcopy since there is no way with gcc to
>> declare section flags in an architecture-agnostic way.
>>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
>> ---
>>  drivers/misc/Makefile       |  7 +++++++
>>  drivers/misc/lkdtm.h        |  6 ++++++
>>  drivers/misc/lkdtm_core.c   | 24 +++++++++++++++++-------
>>  drivers/misc/lkdtm_rodata.c | 10 ++++++++++
>>  4 files changed, 40 insertions(+), 7 deletions(-)
>>  create mode 100644 drivers/misc/lkdtm.h
>>  create mode 100644 drivers/misc/lkdtm_rodata.c
>
> This is blowing up my linker :(
>
>   scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault      (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>
> Haven't had a chance to debug it further.

Argh. Do you want a quick fix for this now? I can add a PPC CONFIG
blacklist for the rodata check, maybe?

Also, what version of gcc? I'll see if I can reproduce this with a
cross compiler...

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

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Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re:  [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section) Kees Cook <keescook@chromium.org> - 2016-08-01 22:00 +0200
  Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section) Michael Ellerman <mpe@ellerman.id.au> - 2016-08-02 05:20 +0200
    Re: [kernel-hardening] Re: Linker segfault on powerpc when  CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function  for testing .rodata section) Kees Cook <keescook@chromium.org> - 2016-08-02 21:20 +0200
      Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section) Michael Ellerman <mpe@ellerman.id.au> - 2016-08-03 07:00 +0200

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