Re: [PATCH v10 02/17] x86_64: add KASan support

[Andrey Ryabinin]

2015-01-31 0:37 GMT+03:00 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>:
> On Fri, 30 Jan 2015 19:15:42 +0300 Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx> wrote:
>
>> >> --- a/lib/Kconfig.kasan
>> >> +++ b/lib/Kconfig.kasan
>> >> @@ -5,6 +5,7 @@ if HAVE_ARCH_KASAN
>> >>
>> >>  config KASAN
>> >>    bool "AddressSanitizer: runtime memory debugger"
>> >> +  depends on !MEMORY_HOTPLUG
>> >>    help
>> >>      Enables address sanitizer - runtime memory debugger,
>> >>      designed to find out-of-bounds accesses and use-after-free bugs.
>> >
>> > That's a significant restriction.  It has obvious runtime implications.
>> > It also means that `make allmodconfig' and `make allyesconfig' don't
>> > enable kasan, so compile coverage will be impacted.
>> >
>> > This wasn't changelogged.  What's the reasoning and what has to be done
>> > to fix it?
>> >
>>
>> Yes, this is runtime dependency. Hot adding memory won't work.
>> Since we don't have shadow for hotplugged memory, kernel will crash on the first access to it.
>> To fix this we need to allocate shadow for new memory.
>>
>> Perhaps it would be better to have a runtime warning instead of Kconfig dependecy?
>
> Is there a plan to get mem-hotplug working with kasan, btw?  It doesn't
> strike me as very important/urgent.  Please add a sentence about this
> to the changelog as well.
>

I don't have a strict plan for this. I could work on this, but not now
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