Re: [PATCH] framewarn: expand KASAN_EXTRA exception to KASAN

Andrey Konovalov
2018-09-21T12:11:59Z

On Fri, Sep 21, 2018 at 10:42 AM, 'Dmitry Vyukov' via kasan-dev
<kasan-dev@googlegroups.com> wrote:
> On Fri, Sep 21, 2018 at 3:50 AM, Andy Lutomirski <luto@kernel.org> wrote:
>> This patch seems reasonable, but you emailed the wrong people :)
>>
>> On Thu, Sep 20, 2018 at 5:15 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>>>
>>> It turns out that KASAN in general will bloat stack frames in unexpected
>>> ways, not just KASAN_EXTRA. So, this patch trivially changes that
>>> default to be associated with KASAN instead of KASAN_EXTRA.
>>>
>>> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
>>> ---
>>> lib/Kconfig.debug | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
>>> index 4966c4fbe7f7..39078a080e29 100644
>>> --- a/lib/Kconfig.debug
>>> +++ b/lib/Kconfig.debug
>>> @@ -222,7 +222,7 @@ config ENABLE_MUST_CHECK
>>> config FRAME_WARN
>>> int "Warn for stack frames larger than (needs gcc 4.4)"
>>> range 0 8192
>>> - default 3072 if KASAN_EXTRA
>>> + default 3072 if KASAN
>>> default 2048 if GCC_PLUGIN_LATENT_ENTROPY
>>> default 1280 if (!64BIT && PARISC)
>>> default 1024 if (!64BIT && !PARISC)
>
>
> Looks fine to me.
> KASAN always increases stack size too for exactly that reason, so it's
> reasonable to allow larger frames rather than try to massage code
> every here and there to fit into the normal frame size.

Do we need KASAN_EXTRA then at all?