[Bug c++/62017] AddressSanitizer reports *-buffer-overflow in destructor when multiple virtual inheritance is used

["chefmax at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62017

Maxim Ostapenko <chefmax at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |chefmax at gcc dot gnu.org

--- Comment #2 from Maxim Ostapenko <chefmax at gcc dot gnu.org> ---
Here another reprocase (diamond inheritance):
======================

struct A {
  int x;
  virtual ~A() {}
};

struct B: public virtual A {
};

struct C: public virtual A {
};

struct D: public B, virtual public C {
};

int main() {
  D d;
}


==24761==ERROR: AddressSanitizer: stack-buffer-overflow on address
0x7ffff1d86bf8 at pc 0x400e1b bp 0x7ffff1d86b70 sp 0x7ffff1d86b68
WRITE of size 24 at 0x7ffff1d86bf8 thread T0
    #0 0x400e1a in C::~C() (/home/max/build/gcc-upstream-x86_64/a.out+0x400e1a)
    #1 0x401257 in D::~D() (/home/max/build/gcc-upstream-x86_64/a.out+0x401257)
    #2 0x400a8b in main (/home/max/build/gcc-upstream-x86_64/a.out+0x400a8b)
    #3 0x7f7487a1676c in __libc_start_main
(/lib/x86_64-linux-gnu/libc.so.6+0x2176c)
    #4 0x400918 (/home/max/build/gcc-upstream-x86_64/a.out+0x400918)

Address 0x7ffff1d86bf8 is located in stack of thread T0 at offset 56 in frame
    #0 0x400a17 in main (/home/max/build/gcc-upstream-x86_64/a.out+0x400a17)

  This frame has 1 object(s):
    [32, 64) 'd' <== Memory access at offset 56 partially overflows this
variable
HINT: this may be a false positive if your program uses some custom stack
unwind mechanism or swapcontext
      (longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow ??:0 C::~C()
Shadow bytes around the buggy address:
  0x10007e3a8d20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8d30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8d40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8d50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8d60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x10007e3a8d70: 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00[00]
  0x10007e3a8d80: f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8d90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8da0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8db0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x10007e3a8dc0: 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
  Heap right redzone:      fb
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack partial redzone:   f4
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  ASan internal:           fe
==24761==ABORTING

Compiled with recent GCC version:
GNU C++ (GCC) version 5.0.0 20140916 (experimental) (x86_64-unknown-linux-gnu)