On Monday, March 31, 2003, at 7:10 PM, Ragnar Sundblad wrote: --On Sun, 30 Mar 2003 23:35:01 -0500 Jim Magee <jmagee@apple.com> wrote: I think you need to read that again. The effect of the no-execute bit is discussed on a page basis, but the bit itself is only settable at the segment level. So, you have to give up 256 MB section(s) of your address space to non-execute status, and you have to assure all stacks are in that range. That was deemed too restrictive at the time. ... I really do think that darwin should have at least non-executable stack, but preferably code should only run from where it has been explicitely allowed to. This os is supposed to also be handled by people who don't have 24 hour watch of CERT advisories. How much work would it be to implement this? Will apple look into doing it? Implement what? We already mark all stacks as read-write-noexecute. But, as I just said, "the hardware can't honor it." Do you want us to change the PowerPC architecture? Or do you think it is worth taking 256MB of virtual address space from each task and making it no-execute, and then forcing all stacks to be in there (requiring many/most programs to be re-built to adapt to it)? We are already under pressure to release some of our reserved address space back to application control. I don't think this will go over all that well with those folks. --Jim _______________________________________________ darwin-kernel mailing list | darwin-kernel@lists.apple.com Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/darwin-kernel Do not post admin requests to the list. They will be ignored.