Nice stack smashing postmortem message

[mcspr]

Wire everything that relies on stack smashing detection to call __stack_chk_fail() (aka what libssp / ssp / stack-protector uses) Expose it in our debugging header

Rename overflow -> smashing, as these are different things we are trying to detect (meaning, that we check for things writing there, not some kind of alloca issue or the way -fstack-check would have worked) ref. #8666

-fstack-protector continues to work as it always did CONT replaces abort(), also moves its check to the loop wrapper to avoid dumping otherwise useless SYS context memory StackThunk replaces a similar abort() call

[mcspr]

btw, something to reproduce failures

#include <Arduino.h> #include <StackThunk.h> #include <umm_malloc/umm_malloc.h> #include <cont.h> #include <user_interface.h> #include <array> // reproduce crash for all three methods, in sequence constexpr uintptr_t RtcMem { 0x60001200 + 128 }; auto* count = reinterpret_cast<volatile uint32_t*>(RtcMem); extern "C" rst_info resetInfo; // there is only a single thunk in the app extern "C" void thunk_failme(); extern "C" void failme() { printf("will ravage %p\n", stack_thunk_ptr); *stack_thunk_ptr = 0xfafafafa; } make_stack_thunk(failme) // needs -fstack-protector to work void ssp_failme() __attribute__((stack_protect)); void ssp_failme() { char buf[4]; strcpy(buf, "ABCDE"); puts(buf); } void setup() { Serial.begin(115200); switch (resetInfo.reason) { case REASON_DEFAULT_RST: case REASON_EXT_SYS_RST: *count = 0; break; } } void loop() { const auto last = *count; *count = ((last + 1) % 3); puts(""); printf("%u - wait for it...\n", last); delay(3000); switch (last) { case 0: g_pcont->stack_guard1 = 0xfafafafa; g_pcont->stack_guard2 = 0xfafafafa; break; case 1: stack_thunk_add_ref(); thunk_failme(); break; case 2: ssp_failme(); break; } }