hasherezade
Unresolved __chkstk call
When the size of all local variables for a function (combined) is greater than the stack page size (4k bytes for x86, 8k bytes for x64) a compiler routine adds a call to __chkstk to the code. This causes a linking error where __chkstk isn't resolved.
Hi @2Trepidatious ! Please share the code snippet, it will be easier for me to test. I will check it soon.
You should be able to replicate it by taking any testing code you already have and just add a char test[10000]; to one of the functions.
The solution is likely to just dynamically allocate something that large instead of putting it on the stack, but I figured it was worth documenting since it happens when the TOTAL size of a function's variables reach the page size and not just a single variable.
The __chkstk documentation says it's added for both x86 and x64, but I've only tried to replicate it with x64. Another potential solution might be that if __chkstk gets added it could just be replaced with the code for __chkstk.
Actually, the above may not be fully true. Here is a better way to replicate the issue:
#include <stdio.h>
#include "peb_lookup.h"
#define CHAR_NUM 10000
int main(void) {
LPVOID kernel32_handle = get_module_by_name((const LPWSTR)L"kernel32.dll");
LPVOID load_lib = get_func_by_name((HMODULE)kernel32_handle, (LPSTR)"LoadLibraryA");
LPVOID get_proc = get_func_by_name((HMODULE)kernel32_handle, (LPSTR)"GetProcAddress");
auto _LoadLibraryA = reinterpret_cast<decltype(&LoadLibraryA)>(load_lib);
auto _GetProcAddress = reinterpret_cast<decltype(&GetProcAddress)>(get_proc);
HMODULE msvcrt_handle = _LoadLibraryA("msvcrt.dll");
decltype(&printf) _printf = reinterpret_cast<decltype(&printf)>(_GetProcAddress((HMODULE)msvcrt_handle, "printf"));
char test[CHAR_NUM];
for (int i =0; i < CHAR_NUM - 1; i++) {
test[i] = 'A';
}
test[CHAR_NUM - 1] = '\0';
_printf(test);
}
