[GH-ISSUE #1811] race condition on portal shutdown #1527

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opened 2026-02-28 01:30:24 +03:00 by kerem · 0 comments

kerem commented

2026-02-28 01:30:24 +03:00

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Originally created by @mnbf9rca on GitHub (Mar 28, 2025).
Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/1811

My code executes the following sequence in case the portal times out:

Parameters cleaned up
Deregistered saveParamsCallback
Cleaning up parameters
Parameters cleaned up
Stopped AP

I've noticed random crashes and following the stack trace, i see it's at the line 966 of WiFiManager.cpp:

> ~/.platformio/packages/toolchain-xtensa-esp32/bin/xtensa-esp32-elf-addr2line -pfiaC -e .pio/build/m5stack-tough/firmware.elf 0x400e9a7c 0x400e9c0c 0x400d444e 0x400d4941 0x400f3dd9
0x400e9a7c: WiFiManager::shutdownConfigPortal() at /Users/rob/Downloads/git/m5-tough/.pio/libdeps/m5stack-tough/WiFiManager/WiFiManager.cpp:966
0x400e9c0c: WiFiManager::stopConfigPortal() at /Users/rob/Downloads/git/m5-tough/.pio/libdeps/m5stack-tough/WiFiManager/WiFiManager.cpp:2540
0x400d444e: doWiFiManager() at /Users/rob/Downloads/git/m5-tough/src/WiFiHelper.cpp:187
0x400d4941: loop() at /Users/rob/Downloads/git/m5-tough/src/main.cpp:72
0x400f3dd9: loopTask(void*) at /Users/rob/.platformio/packages/framework-arduinoespressif32/cores/esp32/main.cpp:50

As far as i can tell, there appears to be a race condition where the code attempts to make one final DNS request after the DNS server resources have already been cleaned up. The dnsServer pointer becomes invalid but the code still tries to access it.

Originally created by @mnbf9rca on GitHub (Mar 28, 2025). Original GitHub issue: https://github.com/tzapu/WiFiManager/issues/1811 My code executes the following sequence in case the portal times out: - Parameters cleaned up - Deregistered saveParamsCallback - Cleaning up parameters - Parameters cleaned up - Stopped AP I've noticed random crashes and following the stack trace, i see it's at the line [966 of WiFiManager.cpp](https://github.com/tzapu/WiFiManager/blob/master/WiFiManager.cpp#L966): ``` > ~/.platformio/packages/toolchain-xtensa-esp32/bin/xtensa-esp32-elf-addr2line -pfiaC -e .pio/build/m5stack-tough/firmware.elf 0x400e9a7c 0x400e9c0c 0x400d444e 0x400d4941 0x400f3dd9 0x400e9a7c: WiFiManager::shutdownConfigPortal() at /Users/rob/Downloads/git/m5-tough/.pio/libdeps/m5stack-tough/WiFiManager/WiFiManager.cpp:966 0x400e9c0c: WiFiManager::stopConfigPortal() at /Users/rob/Downloads/git/m5-tough/.pio/libdeps/m5stack-tough/WiFiManager/WiFiManager.cpp:2540 0x400d444e: doWiFiManager() at /Users/rob/Downloads/git/m5-tough/src/WiFiHelper.cpp:187 0x400d4941: loop() at /Users/rob/Downloads/git/m5-tough/src/main.cpp:72 0x400f3dd9: loopTask(void*) at /Users/rob/.platformio/packages/framework-arduinoespressif32/cores/esp32/main.cpp:50 ``` As far as i can tell, there appears to be a race condition where the code attempts to make one final DNS request after the DNS server resources have already been cleaned up. The dnsServer pointer becomes invalid but the code still tries to access it.