Re: [PATCH] Protection for exploiting null dereference using mmap

[Pavel Machek <pavel@ucw.cz>]

Hi!

> > While I understand, there are a few users who will have problems with
> > this default are we really better to not provide this defense in depth
> > for the majority of users and let those with problems turn it off rather
> > than provide no defense by default?  I could even provide a different
> > default for SELinux and non-SELinux if anyone saw value in that?  But if
> > others think that off default is  best I'll send another patch shortly
> > with the unsigned long fix and the default set to 0.  My hope is then
> > that distros will figure out to turn this on.
> > 
> 
> I hope not.  This breaks any hardware virtualizer.
> 
> So yes, we're better off not having this on, and require it to be
> explicitly enabled by the end user.

You could do something like 4G+4G patches.... but performance penalty
would be ugly.

But no, we cant break userspace 'by default'.
							Pavel

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