GNU OSC (Object Size Checking)

[Jonathan Wakely]

On 6 February 2018 at 20:19, Martin Sebor wrote:
> But no runtime protection happens for libstdc++ containers,
> even with _FORTIFY_SOURCE, because libstdc++ either uses
> the GCC built-in functions (__builtin_memcpy) directly or
> "rolls" its own loops (std::copy, etc.) that GCC transforms
> into calls to the non-checking built-ins.  For the former,
> it might be worth considering using the checking built-ins
> instead.  Jonathan will know best if this would make sense
> and how much it might benefit.  For the latter, I'm sure
> there are opportunities for GCC to do better and check
> the bounds of the copies either before emitting calls to
> these functions or propagating their bounds.

My completely unsubstantiated guess is that people might pass
out-of-bounds pointers to std::string members more often than other
containers.

We certainly could add more checking, but I don't know if it's worth
prioritizing. There are thousands of things we could do with more
hands to do the work.

I've opened https://gcc.gnu.org/PR84256 so it isn't forgotten.