Re: [PATCH v8 1/5] kasan: support backing vmalloc space with real shadow memory

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



>>> @@ -2497,6 +2533,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
>>>  	if (!addr)
>>>  		return NULL;
>>>  
>>> +	if (kasan_populate_vmalloc(real_size, area))
>>> +		return NULL;
>>> +
>>
>> KASAN itself uses __vmalloc_node_range() to allocate and map shadow in memory online callback.
>> So we should either skip non-vmalloc and non-module addresses here or teach kasan's memory online/offline
>> callbacks to not use __vmalloc_node_range() (do something similar to kasan_populate_vmalloc() perhaps?). 
>
> Ah, right you are. I haven't been testing that.
>
> I am a bit nervous about further restricting kasan_populate_vmalloc: I
> seem to remember having problems with code using the vmalloc family of
> functions to map memory that doesn't lie within vmalloc space but which
> still has instrumented accesses.

I was wrong or remembering early implementation bugs.

If the memory we're allocating in __vmalloc_node_range falls outside of
vmalloc and module space, it shouldn't be getting shadow mapped for it
by kasan_populate_vmalloc. For v9, I've guarded the call with
is_vmalloc_or_module. It seems to work fine when tested with hotplugged
memory.

Thanks again.

Regards,
Daniel

> On the other hand, I'm not keen on rewriting any of the memory
> on/offline code if I can avoid it!
>
> I'll have a look and get back you as soon as I can.
>
> Thanks for catching this.
>
> Kind regards,
> Daniel
>
>>
>> -- 
>> You received this message because you are subscribed to the Google Groups "kasan-dev" group.
>> To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@xxxxxxxxxxxxxxxx.
>> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/352cb4fa-2e57-7e3b-23af-898e113bbe22%40virtuozzo.com.




[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [eCos]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux