Bugtraq mailing list archives
Re: http://www.smashguard.org
From: Pavel Machek <pavel () ucw cz>
Date: Fri, 30 Apr 2004 01:29:21 +0200
Hi!
Computer World, January 15, 2004).As Theo said, the AMD buffer overflow "protection" is nothing more than sensible separation of R and X bits per page, fixing a glaring andActually it is not "sensible", and it is not separation. You can have r--, r-x, but you can't have --x.But that is *exactly* what is meant by "separation" of R and X. I have no idea what you mean by it not being "sensible". Most every CPU I have ever seen does this except the x86. Someone apparently thought there was no value in separate R and X bits for the i386 back in the mid-80s. It was a false economy :)
Well.. they are not really separate bits. If they was, you'd have ---, --x, r--, r-x. You can't have --x combination (which is sad for the emulators). I believe that on most sane architectures (m68k at least), you can have all 4 combinations. Pavel -- 934a471f20d6580d5aad759bf0d97ddc
Current thread:
- Re: http://www.smashguard.org Pavel Machek (Apr 30)
- Re: http://www.smashguard.org Crispin Cowan (Apr 30)
- Re: http://www.smashguard.org Pavel Machek (Apr 30)
- Re: http://www.smashguard.org Nicholas Weaver (May 01)
- Re: http://www.smashguard.org Theo de Raadt (May 01)
- Re: http://www.smashguard.org Pavel Machek (Apr 30)
- Re: http://www.smashguard.org Coleman Kane (May 01)
- Re: http://www.smashguard.org Theo de Raadt (May 01)
- Re: http://www.smashguard.org Crispin Cowan (Apr 30)