[erlang-questions] enif_send() and overrun heap

[Guilherme Andrade]

On 7 August 2018 at 11:23, Guilherme Andrade <g@REDACTED> wrote:

> I've distilled the flow that triggers the crash and made a demo.
>
>     https://github.com/g-andrade/enif_send_crash
>
> It implements a dirty NIF which sends messages to a second process using
> enif_send() and a message containing a heap-allocated term.
> It increases the number of iterations exponentially until it crashes.
>

I've also created an issue[1] in the bug tracker after someone privately
suggested it to me.

[1]: https://bugs.erlang.org/browse/ERL-695



>
> This is what happens in my machine very consistently (macOS):
>
> > ./enif_send_crash
> > Trying to crash (1 iterations)...
> > Trying to crash (2 iterations)...
> > Trying to crash (4 iterations)...
> > Trying to crash (8 iterations)...
> > Trying to crash (16 iterations)...
> > Trying to crash (32 iterations)...
> > Trying to crash (64 iterations)...
> > Trying to crash (128 iterations)...
> > Trying to crash (256 iterations)...
> > Trying to crash (512 iterations)...
> > Trying to crash (1024 iterations)...
> > beam/erl_nif.c:445:cache_env() Assertion failed: env->hp_end ==
> (env->proc)->stop
>
>
> On 7 August 2018 at 09:38, Guilherme Andrade <g@REDACTED> wrote:
>
>> Hi,
>>
>> On 20 June 2018 at 18:39, Sverker Eriksson <sverker.eriksson@REDACTED
>> > wrote:
>>
>>> I suggest you (and everybody during NIF development) to run on a
>>> debug-VM.
>>> It's slower but it catches a lot of faults earlier and produces a nicer
>>> core
>>> dump. It will catch enif_* API violations such as building
>>> tuples/lists/maps
>>> with terms from different environments.
>>>
>>
>> I finally found the time to look into this matter again.
>>
>> Using a debug build of the VM (20.3), the crash consistently happens due
>> to a failed assertion in line 445 of erl_nif.c[1].
>> Other conditions are the same as before.
>>
>> Is this enlightening in anyway? I've got a 2.8 GiB core dump I can look
>> into if you tell me that's the right direction to go.
>>
>>
>> [1]: https://github.com/erlang/otp/blob/OTP-20.3.8.4/erts/emulato
>> r/beam/erl_nif.c#L445
>>
>> --
>> Guilherme
>>
>
>
>
> --
> Guilherme
>



-- 
Guilherme
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://erlang.org/pipermail/erlang-questions/attachments/20180807/b212db5b/attachment.htm>