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From: Daniel Axtens <dja@axtens.net>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	kasan-dev@googlegroups.com, linux-mm@kvack.org, x86@kernel.org,
	glider@google.com, luto@kernel.org, linux-kernel@vger.kernel.org,
	mark.rutland@arm.com, dvyukov@google.com,
	christophe.leroy@c-s.fr
Cc: linuxppc-dev@lists.ozlabs.org, gor@linux.ibm.com
Subject: Re: [PATCH v8 1/5] kasan: support backing vmalloc space with real shadow memory
Date: Tue, 15 Oct 2019 17:29:40 +1100	[thread overview]
Message-ID: <878spmttbf.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <87ftjvtoo7.fsf@dja-thinkpad.axtens.net>

>>> @@ -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
>
>>
>> -- 
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>> To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/352cb4fa-2e57-7e3b-23af-898e113bbe22%40virtuozzo.com.


  parent reply	other threads:[~2019-10-15  6:29 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-01  6:58 [PATCH v8 0/5] kasan: support backing vmalloc space with real shadow memory Daniel Axtens
2019-10-01  6:58 ` [PATCH v8 1/5] " Daniel Axtens
2019-10-01 10:17   ` Uladzislau Rezki
2019-10-02  1:23     ` Daniel Axtens
2019-10-02  7:13       ` Christophe Leroy
2019-10-02 11:49       ` Uladzislau Rezki
2019-10-07  8:02   ` Uladzislau Rezki
2019-10-11  5:15     ` Daniel Axtens
2019-10-11 19:57   ` Andrey Ryabinin
2019-10-14 13:57     ` Daniel Axtens
2019-10-14 15:27       ` Mark Rutland
2019-10-15  6:32         ` Daniel Axtens
2019-10-15  6:29       ` Daniel Axtens [this message]
2019-10-16 12:19       ` Andrey Ryabinin
2019-10-16 13:22         ` Mark Rutland
2019-10-18 10:43           ` Andrey Ryabinin
2019-10-28  7:39             ` Daniel Axtens
2019-10-28  1:26           ` Daniel Axtens
2019-10-14 15:43   ` Mark Rutland
2019-10-15  6:27     ` Daniel Axtens
2019-10-01  6:58 ` [PATCH v8 2/5] kasan: add test for vmalloc Daniel Axtens
2019-10-01  6:58 ` [PATCH v8 3/5] fork: support VMAP_STACK with KASAN_VMALLOC Daniel Axtens
2019-10-01  6:58 ` [PATCH v8 4/5] x86/kasan: support KASAN_VMALLOC Daniel Axtens
2019-10-01  6:58 ` [PATCH v8 5/5] kasan debug: track pages allocated for vmalloc shadow Daniel Axtens

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