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From: radford@calgary.UUCP
Newsgroups: comp.os.minix
Subject: Re: Memory handling in MINIX ?
Message-ID: <772@vaxb.calgary.UUCP>
Date: Tue, 27-Jan-87 13:57:17 EST
Article-I.D.: vaxb.772
Posted: Tue Jan 27 13:57:17 1987
Date-Received: Fri, 30-Jan-87 05:25:15 EST
References: <5490004@nucsrl.UUCP> <254@hqda-ai.UUCP>
Organization: U. of Calgary, Calgary, Ab.
Lines: 16
Summary: Can C programs crash the system?

In article <254@hqda-ai.UUCP>, merlin@hqda-ai.UUCP (David S. Hayes) writes:

> ... There is a 
> "gentlemen's agreement" that no one writes anywhere but in their
> data segment, which is referenced by the DS or SS segment
> registers.  The C compiler abides by this.  However, someone
> writing in assembler *could* overwrite anything they chose.

Are procedure return addresses stored in this data space? If so,
a C program can still crash the machine by altering a return address,
returning to some random piece of code, and writting all over everything.

Does anyone know how difficult it would be to make MINIX totally 
secure against crashes by programs written only in C?

     Radford Neal