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SubjectRe: more build problems with "Makefile: move stackprotector availability out of Kconfig"
On Tue, Oct 17, 2017 at 5:26 PM, Kees Cook <> wrote:
> On Tue, Oct 17, 2017 at 8:23 AM, Arnd Bergmann <> wrote:
>> On Tue, Oct 17, 2017 at 1:00 PM, Arnd Bergmann <> wrote:
>>> Hi Kees,
>>> On my test box, current linux-next kernels fail to build due to the
>>> patch that introduces CONFIG_CC_STACKPROTECTOR_AUTO, with my mainline
>>> gcc
>>> builds up to gcc-5.5.0. gcc-6 and higher work fine, as
>>> scripts/ returns 'y' for those.
>>> Using the compilers provided by Ubuntu (4.6/4.7/4.8/4.9), everything
>>> also works as expected, so my interpretation is that mainline gcc did
>>> not enable the stack protector until gcc-6, while distributions did.
>>> Do you agree with that interpretation?
>> It's probably a little different. I tried bisecting the gcc commit that fixed
>> the issue for me, and ended up with this commit
>> that caused the target to change from x86_64-unknown-linux to
>> x86_64-pc-linux, and apparently caused the compiler bootstrap
>> to incorrectly identify the capabilities of the assembler. As a result,
>> the assembler output inside of scripts/
>> that should be
>> [snip]
> Yeah, %gs: vs __stack_chk_guard global.
> Do you know which gccs (of the past) had this?

The commit I linked to went into gcc-6.1.0, everything before that
version is affected for me. I tried gcc-4.{3,4,5,6,7,8,9} and gcc-5.5.

I'm still trying to figure out which part of the config.guess change
caused exactly fixed it and why.


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