Re: Security fix for remapping of page 0 (was [PATCH] ChangeZERO_SIZE_PTR to point at unmapped space)

[Linus Torvalds]

On Wed, 3 Jun 2009, Larry H. wrote:
> > 
> > The fact, the NULL pointer attack is neither easy nor common. It's 
> > perfectly reasonable to say "we'll allow mmap at virtual address zero".
> 
> And how could you calibrate if this attack venue isn't easy to take
> advantage of? Or not commonly abused? What empirical results led you to this
> conclusion?

It's not a primary attack vector. You need to have already broken local 
security to get there - you need to be able to execute code.

That means that you've already by-passed all the main security. It's thus 
by definition less common than attack vectors like buffer overflows that 
give you that capability in the first place.

			Linus
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/