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c++macosgcccrashvtable

Under what circumstances can a vtable pointer be null (or 0x1)?

I am currently debugging a crashlog. The crash occurs because the vtable pointer of a (c++-) object is 0x1, while the rest of the object seems to be ok as far as I can tell from the crashlog.

The program crashes when it tries to call a virtual method.

My question: Under what circumstances can a vtable pointer become null? Does operator delete set the vtable pointer to null?

This occurs on OS X using gcc 4.0.1 (Apple Inc. build 5493).

Solution

  • Could be a memory trample - something writing over that vtable by mistake. There is a nearly infinite amount of ways to "achieve" this in C++. A buffer overflow, for example.