Past The End iterator dereference in filter_iterator

Riproduci l’esempio dell’issue con GCC e ASAN, quindi esamina boost/iterator/filter_iterator.hpp per seguire la gestione dell’iteratore di fine. Il lavoro è completato quando il predicato sempre falso non dereferenzia più oltre l’intervallo e l’esempio termina senza un errore di ASAN.

This simple test program segfaults on my GCC box with Boost 1.78

#include <boost/iterator/filter_iterator.hpp>
#include <iostream>
#include <array>

int main() {
    struct False { bool operator()(unsigned char) const { return false; } };

    std::array<char, 3> const s{'A','B','C'};
    using FIt = boost::iterators::filter_iterator<False, const char*>;

    for (FIt it(False{}, s.begin(), s.end()), end(s.end()); it != end; ++it) {
        std::cout << static_cast<int>(*it) << " ";
    };
}

See it live with ASAN: https://godbolt.org/z/8c9f1drGn

=================================================================
==1==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffc00329dc3 at pc 0x0000004fc947 bp 0x7ffc00329d90 sp 0x7ffc00329d88
READ of size 1 at 0x7ffc00329dc3 thread T0
    #0 0x4fc946 in main /app/example.cpp:12:39
    #1 0x7f90b8b920b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x240b2)
    #2 0x41f34d in _start (/app/output.s+0x41f34d)

Address 0x7ffc00329dc3 is located in stack of thread T0 at offset 35 in frame
    #0 0x4fc853 in main /app/example.cpp:5

  This frame has 1 object(s):
    [32, 35) 's' (line 8) <== Memory access at offset 35 overflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow /app/example.cpp:12:39 in main
Shadow bytes around the buggy address:
  0x10000005d360: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d370: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d390: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d3a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10000005d3b0: 00 00 00 00 f1 f1 f1 f1[03]f3 f3 f3 00 00 00 00
  0x10000005d3c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d3d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d3e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d3f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10000005d400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==1==ABORTING