[PATCH] Omit frame pointer and fix %ebp by default on x86 (take 3)

[Florian Weimer]

* Roger Sayle:

> Taking a slightly different tack, preserving the frame pointer in
> executables that don't need it is a potential security vulnerability.
> The ability to walk back through stack frames inspecting PCs allows
> a "code insertion/buffer overflow" attack to subvert even recent
> position-independent-executable (PIE) security polices.  By knowing
> how many frames deep an exploit is within a known executable, the
> attacking code can unwind to a known reference point in both the
> executable, libc and maybe even the kernel.  Once the exploit has
> the relocated address of __libc_start_main in libc.so, its possible
> to invoke system library functions without link-time support.

I think it's possible to rewind the stack from the ground up once you
can read it, so I doubt -fomit-frame-pointer buys you anything from a
security perspective.