Re: [RFC, PATCHv2 29/29] mm, x86: introduce RLIMIT_VADDR

[Arnd Bergmann]

On Tuesday, January 3, 2017 10:29:33 AM CET Andy Lutomirski wrote:
> 
> Hmm.  What if we approached this a bit differently?  We could add a
> single new personality bit ADDR_LIMIT_EXPLICIT.  Setting this bit
> cause PER_LINUX32_3GB etc to be automatically cleared.

Both the ADDR_LIMIT_32BIT and ADDR_LIMIT_3GB flags I guess?

> When
> ADDR_LIMIT_EXPLICIT is in effect, prctl can set a 64-bit numeric
> limit.  If ADDR_LIMIT_EXPLICIT is cleared, the prctl value stops being
> settable and reading it via prctl returns whatever is implied by the
> other personality bits.

I don't see anything wrong with it, but I'm a bit confused now
what this would be good for, compared to using just prctl.

Is this about setuid clearing the personality but not the prctl,
or something else?

	Arnd