# Re: \[bug\] stack protector panics on v4.10-rc1+

- From: Michael Ellerman \<mpe@ellerman.id.au\>
- Date: 2017-01-24 03:41:59 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2017/01/9494766
- Thread: https://ratatoskr.run/linuxppc-dev/2017/01/9494763/t.md

```text
Segher Boessenkool [ref] writes:

> On Mon, Jan 23, 2017 at 07:10:00PM -0500, Jan Stancek wrote:
>> I'm running into panics with stack protector enabled on ppc64le
>
>> I came across following gcc commit:
>>   https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=0d55f4d0aeaeb16629a2c07c96a190695b83a7e6
>> which mentions offset above:
>>   "If TARGET_THREAD_SSP_OFFSET is defined, use -0x7010(13) resp.
>>    -0x7008(2) instead of reading __stack_chk_guard variable."
>> 
>> It looks like it's not reading canary value from __stack_chk_guard variable.
>> atm. I'm not sure where -28688(r13) falls in ppc kernel (somewhere near paca struct?).
>> 
>> Is anyone else seeing these panics?
>
> Everyone is.

Are they? I'm not?

> This is fixed in GCC 8 (and will be backported to GCC 7 and GCC 6 and
> maybe even GCC 5).  See <http://gcc.gnu.org/r244556> (and r244562 and
> r244677).

# cat /proc/version 
Linux version 4.10.0-rc5-compiler_gcc-6.3.0-00006-ge357eb97a6be (michael@ka3.ozlabs.ibm.com) (gcc version 6.3.0 (Custom 4b5e15daff8b5444) ) #558 SMP Tue Jan 24 14:29:04 AEDT 2017

# zgrep STACKPROTECTOR /proc/config.gz 
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_CC_STACKPROTECTOR=y
CONFIG_CC_STACKPROTECTOR_REGULAR=y

I guess I'm just lucky?

cheers
```