How?


From: Std-Discussion <std-discussion-bounces_at_lists.isocpp.org> On Behalf Of Amit via Std-Discussion
Sent: Monday, February 17, 2025 10:54 AM
To: Jan Schultke <janschultke_at_[hidden]>
Cc: Amit <amitchoudhary0523_at_[hidden]>; std-discussion_at_[hidden]
Subject: Re: [std-discussion] C++ language has a big security hole.

In all C++ object layouts, I have seen that members follow the previous one as in a C structure.

My main point is that hackers/bad people can take advantage of this.

Regards,
Amit


On Mon, Feb 17, 2025, 3:17 PM Jan Schultke <janschultke_at_[hidden]<mailto:janschultke_at_[hidden]>> wrote:
Your code has undefined behavior because you cannot obtain your j_ptr
by doing i_ptr + 1. A past the end pointer is not a pointer to the
next member.

However, the example is correct without j_ptr. It is possible to
obtain a pointer to the first member of a standard-layout class such
as MyClass, even if that member is private.

I wouldn't really call it a security hole. The only way you will do
this in idiomatic C++ code is with reinterpret_cast, and
reinterpret_cast is a giant red flag which says "I'm an expert, I know
what I'm doing, and what I'm doing is potentially dangerous". This
never happens by accident.