valgrind partially broken by current hardy-proposed kernel?

Ben Collins ben.collins at canonical.com
Wed Jun 4 15:33:00 UTC 2008


On Wed, 2008-06-04 at 08:12 -0700, Kees Cook wrote:
> Hi,
> 
> On Wed, Jun 04, 2008 at 01:30:55PM +0100, Matthew Garrett wrote:
> > On Mon, Jun 02, 2008 at 03:07:10PM -0700, Kees Cook wrote:
> > 
> > > True, but the mmap_min_addr setting only affects MAP_FIXED, in which
> > > you really want address 0.  (And yes, that's valid, but not common.)
> > > The common use-case of use NULL to just get an arbitrary mapping is done
> > > without MAP_FIXED.
> > 
> > vbetool needs to map address 0 with MAP_FIXED in order to get the IDT.
> 
> Yes, but it (and usplash) run as root, which is exempt from this check.
> (Wine and dosemu use this area as well, and for those use cases, people
> have been advised to change the limit back to 0.  For the default use-cases,
> there is no problem.)

So what danger is imposed by the non-root use case being able to mmap
below 64k?





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