Crash on connection close

[the-programmer]

So, first off, I have no idea how this crash happend. But today the ESP32 unexpectedly crashed. So, as a precaution I grabbed everything I could find. (it only happend once so far).

[108839][D][ESP32AsyncFtpClient.cpp:234] sendCommand(): FTP >>> QUIT
Guru Meditation Error: Core  0 panic'ed (LoadProhibited). Exception was unhandled.

Core  0 register dump:
PC      : 0x400d87fb  PS      : 0x00060e30  A0      : 0x800d8930  A1      : 0x3ffb9170  
A2      : 0x00000000  A3      : 0x3ffd2e14  A4      : 0x00000000  A5      : 0x3ffc75c4  
A6      : 0x3ffc75dc  A7      : 0x00000000  A8      : 0x80091e80  A9      : 0x3ffb9170  
A10     : 0x3ffd318c  A11     : 0x3ffd318c  A12     : 0x00001672  A13     : 0x00000b40  
A14     : 0x00000000  A15     : 0x00000001  SAR     : 0x00000014  EXCCAUSE: 0x0000001c  
EXCVADDR: 0x00000000  LBEG    : 0x40089df8  LEND    : 0x40089e0e  LCOUNT  : 0xffffffff  


Backtrace: 0x400d87f8:0x3ffb9170 0x400d892d:0x3ffb91b0 0x40107e01:0x3ffb91e0 0x4010cbe2:0x3ffb9250 0x40112002:0x3ffb9280 0x40101bfd:0x3ffb92a0

The stacktrace decoded to

0x400d87fb: AsyncClient::_lwip_fin(tcp_pcb*, signed char) at c:\[...].pio/libdeps/esp32dev/AsyncTCP/src\AsyncTCP.cpp:1072
0x400d87f8: AsyncClient::_lwip_fin(tcp_pcb*, signed char) at c:\[...].pio/libdeps/esp32dev/AsyncTCP/src\AsyncTCP.cpp:1071
0x400d892d: AsyncTCP_detail::tcp_recv(void*, tcp_pcb*, pbuf*, signed char) at c:\[...].pio/libdeps/esp32dev/AsyncTCP/src\AsyncTCP.cpp:464
0x40107e01: tcp_input at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/core/tcp_in.c:541
0x4010cbe2: ip4_input at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/core/ipv4/ip4.c:803
0x40112002: ethernet_input at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/netif/ethernet.c:186
0x40101bfd: tcpip_thread_handle_msg at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/api/tcpip.c:180
0x40101bfd: tcpip_thread at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/lwip/lwip/src/api/tcpip.c:154

With the following code at AsyncTCP.cpp:1072 (in platformio.ini I have: esp32async/AsyncTCP@=3.4.0)

int8_t AsyncClient::_lwip_fin(tcp_pcb *pcb, int8_t err) {
  if (!_pcb || pcb != _pcb) { // <------- Line 1072
    log_d("0x%08" PRIx32 " != 0x%08" PRIx32, (uint32_t)pcb, (uint32_t)_pcb);
    return ERR_OK;
  }

As well as the full data exchanged by this socket Strange crash.zip.
The IP of the ESP32 is 10.79.100.67.

[mathieucarbou]

The stack trace is strange in comparison to the code! if (!_pcb || pcb != _pcb) => how could it crash...

By the way, are you running with -D CONFIG_ASYNC_TCP_RUNNING_CORE=1 to avoid any potentiel concurrent issues with tasks sharing data between 2 cores ?

[the-programmer]

No. It's default. But I'll set that to be safe.
My (best) guess is that pcb somehow is NULL. But I have no clue on how that would be possible.

If I have more of this issue, I'll post an update.

[mathieucarbou]

even if pcb was NULL, why this line would fail...

That's why I am wondering if this is a concurrent issues - 2 cores trying to access same pointer maybe ?

[the-programmer]

As said, I only seen it once. So for now I just logged it here and added -D CONFIG_ASYNC_TCP_RUNNING_CORE=1 (as recommended) to platformio.ini.
Now it's a waiting game.. 😉

[willmmiles]

Most likely it's failing because the this pointer is invalid, so it can't dereference this->_pcb. Are you by any chance using a platform without CONFIG_LWIP_TCPIP_CORE_LOCKING, eg. one of the "arduino-2" type builds?