Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!usc!ginosko!aplcen!haven!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: effect of free()
Message-ID: <10971@smoke.BRL.MIL>
Date: 7 Sep 89 11:41:18 GMT
References: <319@cubmol.BIO.COLUMBIA.EDU> <3756@buengc.BU.EDU> <1989Aug17.005548.745@twwells.com> <16022@vail.ICO.ISC.COM> <248@seti.inria.fr> <246@ssp1.idca.tds.philips.nl>
Reply-To: gwyn@brl.arpa (Doug Gwyn)
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 11

In article <246@ssp1.idca.tds.philips.nl> dolf@idca.tds.PHILIPS.nl (Dolf Grunbauer) writes:
-I agree with Dick, as the original statement is:
-   if (ptr == 0) ...
-I think Martin explained why the statement:
-   if (*ptr == 0) ...
-is unacceptable and how the OS could trigger this illegal use.
-Is this true or am I missing Martin's point ?

No, Martin tried to explain why if(ptr==0) could fail after the free().
There aren't many common architectures where this would be a problem,
but it can happen.