mmap breakage?
Alan Cox
alc at cs.rice.edu
Sun Apr 4 21:20:11 PDT 2004
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@ 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
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