Re: mmap breakage?

On Sunday 04 April 2004 09:56 pm, Alexander Kabaev wrote:
> On Sun, Apr 04, 2004 at 11:20:10PM -0500, Alan Cox wrote:
> > On Mon, Apr 05, 2004 at 12:11:47AM -0400, Alexander Kabaev wrote:
> > > On Sun, Apr 04, 2004 at 03:12:51PM -0500, Alan Cox wrote:
> > > > Alfred,
> > > >
> > > > Please try the attached patch.  This problems appears to be a
> > > > consequence of vm/vm_mmap.c revision 1.180, where as part of a
> > > > much needed code reorganization for locking the check for the
> > > > /dev/zero special case got placed after the permissions check
> > > > for the general case.  This patch simply delays the permissions
> > > > check for devices until you have the necessary lock to also
> > > > check for /dev/zero.
> > > >
> > > > Since kan_at_ authored the reorganization, I'm cc:'ing him on this
> > > > message for purposes of obtaining a review.  (At least one
> > > > comment should be updated to reflect my code changes.)
> > > >
> > > > Regards,
> > > > Alan
> > >
> > > Alan, Alfred,
> > >
> > > I had the following patch which is currently pending a review by
> > > Peter Wemm. I meant to commit it on Friday, but ran out of time:
> > >
> > >
> > >  http://perforce.freebsd.org/chv.cgi?CH=50213
> >
> > I believe that there is a problem with this patch.  Specifically,
> > if maxprot is set to VM_PROT_ALL for devices in mmap(), then the
> > security check in vm_mmap_vnode() has no effect.  Please take a
> > look at the entirety of the changes that I propose to mmap().
> >
> > Regards,
> > Alan
>
> There is a problem indeed. I committed your (correct!) patch instead.
> Thanks!

Heh.  Now I'm glad I suggested that you check with Alan :-)
-- 
Peter Wemm - peter_at_wemm.org; peter_at_FreeBSD.org; peter_at_yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5