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From: Evgenii Stepanov <eugenis@google.com>
Date: Fri, 16 Mar 2018 13:21:01 -0700
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Subject: Re: [RFC PATCH 09/14] khwasan: add hooks implementation
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To: Andrey Konovalov <andreyknvl@google.com>
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On Fri, Mar 16, 2018 at 12:06 PM, Andrey Konovalov
<andreyknvl@google.com> wrote:
> On Fri, Mar 16, 2018 at 7:45 PM, Evgenii Stepanov <eugenis@google.com> wrote:
>> On Fri, Mar 16, 2018 at 11:24 AM, Andrey Konovalov
>> <andreyknvl@google.com> wrote:
>>> Right, by redzones in this case I meant the metadata that is stored
>>> right after the object (which includes alloc and free stack handles
>>> and perhaps some other allocator stuff).
>>
>> Oh, I did not realize we have free (as in beer, not as in
>> use-after-free) redzones between allocations. Yes, reserving a color
>> sounds
>> like a good idea.
>
> OK, I'll do that then.
>
>>
>>>
>>>> As for use-after-free, to catch it with
>>>> 100% probability one would need infinite memory for the quarantine.
>
> As for the second part of Andrey's suggestion (as far as I understand
> it): reserve a color for freed objects. Without quarantine, this
> should give us a precise
> use-after-free-but-without-someone-else-allocating-the-same-object
> detection. What do you think about that?

Still non-deterministic, but we can use the same color we reserved for
the redzones, why not.

>
>>>> It
>>>> is possible to guarantee 100% detection of linear buffer overflow by
>>>> giving live adjacent chunks distinct tags.
>
> I'll add that to the TODO list as well.