Re: CVS commit: src/sys/arch

[David Holland <dholland-sourcechanges%netbsd.org@localhost>]

On Thu, Nov 24, 2016 at 10:28:56PM +0900, Masanobu SAITOH wrote:
 > > Put a one-page redzone between userland and the PTE space on amd64 and
 > > i386.
 > > 
 > > The PTE space is a critical region that maps the page tree, and bugs have
 > > been found in both amd64 and i386 where the kernel would wrongly overflow
 > > userland data on this area. This kind of bug is terrible, since it allows
 > > userland to overwrite some entries of the page tree, which makes it easy
 > > to patch the kernel text and get ring0 privileges.
 > 
 > My emacs dumps core with change.
 > 
 > What should we do?

Make maxv clean up his mess, or rebuild emacs. It seems that the stack
location gets baked in somehow when emacs dumps, although I don't
really see exactly how (see PR 51654) and this causes existing emacs
binaries to stop working.

-- 
David A. Holland
dholland%netbsd.org@localhost