linux-next.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Randy Dunlap <rdunlap@infradead.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
	linux-next@vger.kernel.org, sfr@canb.auug.org.au, mhocko@suse.cz
Subject: Re: mmotm 2014-07-02-15-07 uploaded (stack protector)
Date: Wed, 02 Jul 2014 17:37:36 -0700	[thread overview]
Message-ID: <53B4A5D0.9000702@infradead.org> (raw)
In-Reply-To: <20140703002231.GR19781@tassilo.jf.intel.com>

On 07/02/14 17:22, Andi Kleen wrote:
> On Wed, Jul 02, 2014 at 04:21:06PM -0700, Randy Dunlap wrote:
>> On 07/02/14 15:08, akpm@linux-foundation.org wrote:
>>> The mm-of-the-moment snapshot 2014-07-02-15-07 has been uploaded to
>>>
>>>    http://www.ozlabs.org/~akpm/mmotm/
>>>
>>> mmotm-readme.txt says
>>>
>>> README for mm-of-the-moment:
>>>
>>> http://www.ozlabs.org/~akpm/mmotm/
>>>
>>> This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
>>> more than once a week.
>>
>> Hi Andi,
>>
>> Here is an extract from 10 randconfig builds:
>>
>>
>> $ grep STACKPROTECTOR_STRONG config-r*
>> config-r8735:CONFIG_CC_STACKPROTECTOR_STRONG=y
>> config-r8736:CONFIG_CC_STACKPROTECTOR_STRONG=y
>> config-r8737:# CONFIG_CC_STACKPROTECTOR_STRONG is not set
>> config-r8738:# CONFIG_CC_STACKPROTECTOR_STRONG is not set
>> config-r8739:CONFIG_CC_STACKPROTECTOR_STRONG=y
>> config-r8740:CONFIG_CC_STACKPROTECTOR_STRONG=y
>> config-r8741:CONFIG_CC_STACKPROTECTOR_STRONG=y
>> config-r8742:# CONFIG_CC_STACKPROTECTOR_STRONG is not set
>> config-r8743:# CONFIG_CC_STACKPROTECTOR_STRONG is not set
>> config-r8744:# CONFIG_CC_STACKPROTECTOR_STRONG is not set
>>
>>
>> but the captured output for each one says:
>>
>> grep STACKPROTECTOR_STRONG  build*.out
>> build-r8735.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8736.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8736.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8737.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8739.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8740.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8740.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8741.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8741.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>> build-r8742.out:/local/lnx/MM/mmotm-2014-0702-1507/Makefile:662: Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: -fstack-protector-strong not supported by compiler
>>
>>
>> then the build goes on to produce many errors like this one:
>>
>>   CC      init/do_mounts.o
>> gcc: error: unrecognized command line option '-fstack-protector-strong'
>>
>>
>> Can you explain this, please?  or even better yet, fix it.
> 
> That's the code 
> 
> ifdef CONFIG_CC_STACKPROTECTOR_STRONG
>   stackp-flag := -fstack-protector-strong
>   ifeq ($(call cc-option, $(stackp-flag)),)
>     $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
>               -fstack-protector-strong not supported by compiler)
>   endif
> else
>   # Force off for distro compilers that enable stack protector by default.
>   stackp-flag := $(call cc-option, -fno-stack-protector)
> endif
> endif
> KBUILD_CFLAGS += $(stackp-flag)
> 
> So -fstack-protector-strong itself is never protected by a cc-option call.

ouch.

> You could add it to the stack-flag line, then it would only warn.
> 
>   stackp-flag := $(call cc-option, -fstack-protector-strong)
> 
> It's hard to tell what the original author wanted, perhaps they wanted
> it to error out. It looks intentional. Clearly they didn't think of randconfig
> though.
> 
> Or get a compiler that supports stack protection?

Yeah, I have plans to upgrade, just been too busy.

thanks for your help.
-- 
~Randy

  reply	other threads:[~2014-07-03  0:37 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-02 22:08 mmotm 2014-07-02-15-07 uploaded akpm
2014-07-02 23:21 ` mmotm 2014-07-02-15-07 uploaded (stack protector) Randy Dunlap
2014-07-03  0:22   ` Andi Kleen
2014-07-03  0:37     ` Randy Dunlap [this message]
2014-07-03  0:51     ` Kees Cook
2014-07-03  0:56       ` Andrew Morton
2014-07-03  1:10         ` [PATCH] kbuild: explain stack-protector-strong CONFIG logic Kees Cook
2014-07-03  1:00       ` mmotm 2014-07-02-15-07 uploaded (stack protector) Andi Kleen
2014-07-03  1:13         ` Kees Cook
2014-07-03  0:57   ` Kees Cook
2014-07-03  1:42     ` Randy Dunlap

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=53B4A5D0.9000702@infradead.org \
    --to=rdunlap@infradead.org \
    --cc=ak@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-next@vger.kernel.org \
    --cc=mhocko@suse.cz \
    --cc=sfr@canb.auug.org.au \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).