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

[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

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
>
> 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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