#define STACK_CANARY_VALUE 0xDEADBEEF

char _log_buffer[128];
uint32_t _log_buffer_canary = STACK_CANARY_VALUE;

void my_function(void) {
  // your code bla bla bla

  // This is where you should check the canary before using printf
  if (_log_buffer_canary != STACK_CANARY_VALUE) {
    // Stack corruption detected!
    // Handle the error prolly stop execution or trigger a watchdog
  }

  // Now it is safe hopefully to use printf
  vsnprintf(_log_buffer, sizeof(_log_buffer), "%d", some_variable);
}

#define STACK_CANARY_VALUE 0xDEADBEEF

char _log_buffer[128];
uint32_t _log_buffer_canary = STACK_CANARY_VALUE;

void my_function(void) {
  // your code bla bla bla

  // This is where you should check the canary before using printf
  if (_log_buffer_canary != STACK_CANARY_VALUE) {
    // Stack corruption detected!
    // Handle the error prolly stop execution or trigger a watchdog
  }

  // Now it is safe hopefully to use printf
  vsnprintf(_log_buffer, sizeof(_log_buffer), "%d", some_variable);
}