Description

The following was discovered in #9553. Running tests/lwip on a samr21-xpro asserts after some time (sometimes?!?) - without doing anything:

main(): This is RIOT! (Version: 2018.07-devel-867-ge7deb-515b9e49740c-HEAD)
RIOT lwip test application
Assertion "increment_magnitude <= p->len" failed at /data/riotbuild/riotproject/tests/lwip/bin/pkg/samr21-xpro/lwip/src/core/pbuf.c:583
#! exit 1: powering off

@bergzand was not able to reproduce this behavior on samr-21xpro node in the FIT IoT-LAB testbed/Saclay. @MichelRottleuthner was able to reproduce it (locally).

Steps to reproduce the issue

• build tests/lwip (I used Docker)
• flash to a samr21-xpro node
• wait

Expected results

No output on the terminal

Actual results

Assertion from pbuf in the lwip stack

Versions

Ubuntu 18.04
Docker version 17.12.1