"__stack_chk_fail_local" and the difference between local variables and local array variables

Question

So I am following a textbook example. There is a simple C program writing stuff. It is not using the standard library, the sys calls are written in assembly, the _start subprogram, preparing the main args and exiting is also written in assembly.

When I create a singular variable as the first line of main in hello.c it works fine. When I create an array, like char arr[20], I get the following linker error: Undefined reference to __stack_chk_fail_local, hidden symbol __stack_chk_fail_local ins't defined, final link failed: bad value.

Does anyone have an idea why?

hello.c:

#include "calls.h"

static const char dunno[] = "I don't know how to greet you\n";
static const char hello[] = "Hello, dear ";

static int string_length(const char *str)
{
    int i = 0;
    while(str[i])
        i++;
    return i;
}

int main(int argc, char **argv)
{ 
    char arr[20];  
    if (argc < 2)
    {
        sys_write(1, dunno, sizeof(dunno)-1);
        return 1;
    }

    sys_write(1, hello, sizeof(hello)-1);
    sys_write(1, argv[1], string_length(argv[1]));
    sys_write(1, "\n", 1);

    return 0;
}

calls.h:

#ifndef CALLS_H_SENTRY
#define CALLS_H_SENTRY

int sys_read(int fd, void *buf, int size);
int sys_write(int fd, const void *buf, int size);
extern int sys_errno;

#endif

start.asm:

global _start               ; no_std_lib/start.asm
extern main
section     .text
_start :
            mov ecx, [esp]
            mov eax, esp
            add eax, 4
            push eax
            push ecx
            call main
            add esp, 8
            mov ebx, eax    ; main's return result
            mov eax, 1      ; syscall exit
            int 80h

calls.asm:

global sys_read             ; no_std_lib/calls.asm
global sys_write
global sys_errno

section     .bss
sys_errno   resd 1

section     .text
generic_syscall_3:
            push ebp
            mov ebp, esp
            push ebx
            mov ebx, [ebp+8]    ; descriptor
            mov ecx, [ebp+12]   ; ptr to str start
            mov edx, [ebp+16]   ; size of str
            int 80h
            mov edx, eax
            and edx, 0fffff000h
            cmp edx, 0fffff000h
            jnz .okay
            mov [sys_errno], eax
            mov eax, -1

.okay:      pop ebx
            mov esp, ebp
            pop ebp
            ret

sys_read:   mov eax, 3
            jmp generic_syscall_3
sys_write:  mov eax, 4
            jmp generic_syscall_3