Find causing a segmentation fault - c++

Question

I have a shared library for library interposition with an unordered_map.
The unordered_map is filled and consulted through the execution of an application (when intercepting specifics calls).
If I try to find an element in the constructor of the library, it generates a segmentation fault.
Here is the code for the constructor causing the segmentation fault:
void __attribute__((constructor)) init(void) {
void * address = __builtin_extract_return_addr(__builtin_return_address(0));
printf ("Size: %i\n", stats._regions.size()); // works fine
auto regionIt = stats._regions.find(address);
printf ("Never reached\n");
}
Stats is declared in the header, like this:
class Stats {
public
std::unordered_map<void *, RegionInfo> _regions;
}
As said, if I do the find when intercepting specific calls (not in the constructor), it works fine.

Answer 1

Here is the code for the constructor causing the segmentation fault:
You didn't show how the stats global itself is declared, and without that your code is useless (see also MCVE).
But this is almost certainly an instance of static initialization order fiasco.
How can I test if is SIOF? And fix it if that's the case
The usual way to fix SIOF: instead of declaring stats as a global, make it a function-static and return a reference to it, which guarantees that it will be initialized before you access it:
Stats& get_stats()
{
static Stats stats;
return stats;
}
Your constructor will then look like this:
void __attribute__((constructor)) init(void) {
Stats& stats = get_stats();
// rest as before
}
If this fixes the crash, you'll know that it was an instance of SIOF.