[cfe-dev] [RFC] Linux bots should set MALLOC_PERTURB_

[İsmail Dönmez]

On Tue, Jul 22, 2014 at 2:00 PM, İsmail Dönmez <ismail at donmez.ws> wrote:

> Hi,
>
>
> On Tue, Jul 22, 2014 at 1:58 PM, Alexander Potapenko <glider at google.com>
> wrote:
>
>> IIUC this flag does not make glibc invalidate the _pointers_ to freed
>> memory, it just overwrites the contents of the freed memory with
>> garbage.
>> Picking different flag values results in different garbage values,
>> which may affect the behavior of buggy programs and thus help detect
>> the presence of a read-after-free (not a write-after-free or
>> double-free - the latter is handled by MALLOC_CHECK_).
>> This flag can't be used together with ASan, because ASan replaces the
>> libc allocator with its own one. ASan's use-after-free/double-free
>> detection is far more reliable.
>>
>
> Thanks for your reply! I know Asan and MALLOC_PERTURB_ is now compatible
> but they uncover similar bugs with latter being really lightweight and
> less-capable. But still as in PR20228 it uncovers bugs which Asan didn't
> find (I guess?).
>
>

s/now/not

of course...
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