[Ovmsdev] std::string data corruption (issue #189)

[Mark Webb-Johnson]

Michael,

Espressif’s response (and linking to that other issue) sounds like others are seeing this.

Lousy timing (with Chinese New Year next week), so don’t expect anything quick from Espressif. I guess we’ll just have to live with it until they can find a workaround. It sounds like the issue is at the hardware level and a compiler patch will be needed.

Regards, Mark.

> On 30 Jan 2019, at 3:07 AM, Michael Balzer <dexter at expeedo.de> wrote:
> 
> → https://github.com/espressif/esp-idf/issues/3006 <https://github.com/espressif/esp-idf/issues/3006>
> 
> Regards,
> Michael
> 
> 
> Am 28.01.19 um 20:46 schrieb Michael Balzer:
>> To clarify: the bug is most likely not restricted to the case of building a message in a buffer. It can possibly cause corruptions in any RAM section, so can well be responsible for many/most of the unidentified crashes and stack/heap corruptions we're experiencing.
>> 
>> Regards,
>> Michael
>> 
>> 
>> Am 28.01.19 um 20:43 schrieb Michael Balzer:
>>> For those not following the github discussion: I'm pretty sure I've nailed the bug down.
>>> 
>>> I have reproduced the bug in a simple test project and intend to raise an issue with Espressif on this.
>>> 
>>> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#issuecomment-457965435 <https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#issuecomment-457965435>
>>> 
>>> If you'd like to test this on your module, configure the project to your wifi credentials, then use "make flash". As the test project is small, this normally will not erase your OVMS config partition, but a backup is always recommended.
>>> 
>>> Regards,
>>> Michael
>>> 
>>> 
>>> Am 24.01.19 um 21:19 schrieb Michael Balzer:
>>>> Everyone please have a look at…
>>>> 
>>>> https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#issuecomment-457334248 <https://github.com/openvehicles/Open-Vehicle-Monitoring-System-3/issues/189#issuecomment-457334248>
>>>> 
>>>> Please try to reproduce the bug on your modules.
>>>> 
>>>> I'm open for explanations.
>>>> 
>>>> I thought this might be some copy-on-write bug with std::string, but the gcc 5.x libstdc++ does no longer use that implementation (wouldn't be C++11 compliant as well). I also tried moving all strings to temporary buffers, but modes 5 & 6 eliminated this explanation as well.
>>>> 
>>>> My remaining theories:
>>>> A task writing out of bounds (but only 0-bytes?)
>>>> A hardware issue only affecting some modules
>>>> A hardware issue only affecting some percentage of ESP32 could explain this as well as the strange heap corruptions that seem to affect some modules especially often.
>>>> 
>>>> Regards,
>>>> Michael
>>>> 
>>>> -- 
>>>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>>>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>>> 
>>>> 
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>>> 
>>> -- 
>>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>>> 
>>> 
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>> 
>> -- 
>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
>> 
>> 
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> 
> -- 
> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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