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Re: [kernel-hardening] [PATCH v4 3/8] param: convert some "on"/"off" users to strtobool

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On Wed, Jan 27, 2016 at 1:11 PM, David Brown <david.brown@linaro.org> wrote:
> On Tue, Jan 19, 2016 at 10:08:37AM -0800, Kees Cook wrote:
>
>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>> index 9cc20af58c76..f5ea98490ffa 100644
>> --- a/kernel/time/tick-sched.c
>> +++ b/kernel/time/tick-sched.c
>> @@ -387,20 +388,14 @@ void __init tick_nohz_init(void)
>> /*
>>  * NO HZ enabled ?
>>  */
>> -static int tick_nohz_enabled __read_mostly  = 1;
>> +static bool tick_nohz_enabled __read_mostly  = true;
>> unsigned long tick_nohz_active  __read_mostly;
>> /*
>>  * Enable / Disable tickless mode
>>  */
>
>
> Just discovered this conflicts with a recent patch with
> CONFIG_NO_HZ_COMMON:
>
>         commit 46373a15f65fe862f31c19a484acdf551f2b442f
>         Author: Jean Delvare <jdelvare@suse.de>
>         Date:   Mon Jan 11 17:40:31 2016 +0100
>
>             time: nohz: Expose tick_nohz_enabled
>
> kernel/time/tick-sched.c:390:6: error: conflicting types for
> ‘tick_nohz_enabled’
>         bool tick_nohz_enabled __read_mostly = true;
>              ^
> In file included from kernel/time/tick-internal.h:5:0,
>                 from kernel/time/tick-sched.c:30:
> include/linux/tick.h:101:12: note: previous declaration of
> ‘tick_nohz_enabled’ was here
>         extern int tick_nohz_enabled;
>                    ^

Thanks! Yeah, I noticed this too when rebasing recently.

> Fixing the compilation error, it compiles and boots on arm64, however
> it isn't detecting the write (with the lkdtm test).  I'll continue
> looking into what's preventing this.

I'm going to hope it's something easy like CONFIG_DEBUG_RODATA not being set. :)

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

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[PATCH v4 3/8] param: convert some "on"/"off" users to strtobool Kees Cook <keescook@chromium.org> - 2016-01-19 19:10 +0100
  Re: [kernel-hardening] [PATCH v4 3/8] param: convert some "on"/"off"  users to strtobool Kees Cook <keescook@chromium.org> - 2016-01-27 22:20 +0100
    [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional David Brown <david.brown@linaro.org> - 2016-01-28 01:10 +0100
      Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Kees Cook <keescook@chromium.org> - 2016-01-28 01:20 +0100
        Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-01-28 09:30 +0100
      Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Mark Rutland <mark.rutland@arm.com> - 2016-01-28 12:10 +0100
        Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Kees Cook <keescook@chromium.org> - 2016-01-28 15:10 +0100
          Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Mark Rutland <mark.rutland@arm.com> - 2016-01-28 16:00 +0100
            Re: [PATCH] arm64: make CONFIG_DEBUG_RODATA non-optional Kees Cook <keescook@chromium.org> - 2016-01-28 16:20 +0100
  Re: [kernel-hardening] [PATCH v4 3/8] param: convert some "on"/"off"  users to strtobool David Brown <david.brown@linaro.org> - 2016-01-27 22:20 +0100

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