Messages in this thread | | | Date | Fri, 07 Aug 1998 14:22:58 +0200 | From | Rene Janssen <> | Subject | Re: Compiler alternatives to no-exec (was Re: non exec stack...) |
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At 06:20 AM 8/7/98 GMT, Linus Torvalds wrote: >In article <y7rogtxzkdr.fsf@sytry.doc.ic.ac.uk>, > >Zero also happens to be very cheap to test against. Total overhead: four >instructions per function > >+ pushl $0 > ... >+ popl %ecx >+ testl %ecx,%ecx >+ jne abort > ret >
This is probably not sufficient for all cases. You have to put 2 zero guard bytes around the return address to be more secure. Overwriting the returnadress can be done from two directions in theory.
Cheers,
René
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