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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!simtel!news.kei.com!news.mathworks.com!gatech!swrinde!cs.utexas.edu!venus.sun.com!nntp-hub2.barrnet.net!nntp-sc.barrnet.net!netapp.com!netapp.com!not-for-mail From: guy@netapp.com (Guy Harris) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Major strcmp bug under BSD 2.0? Date: 5 Jun 1995 15:47:04 -0700 Organization: Network Appliance Corporation Lines: 22 Message-ID: <3r01h8$lp7@nova.netapp.com> References: <3qfn52$188j@troy.la.locus.com> <3qo3m8$aq7@park.uvsc.edu> <3qqm6i$d5m@cynjut.neonramp.com> NNTP-Posting-Host: 192.9.200.13 In article <3qo3m8$aq7@park.uvsc.edu>, Terry Lambert <terry@cs.weber.edu> wrote: >This is a result of the intentional unmapping of page 0 to catch >NULL pointer dereferences with a kernel "page not present" error. > >SunOS and Solaris do the same thing. Dave Burgess <burgess@cynjut.neonramp.com> wrote: >Not to beat a dead horse unnecessarily, but didn't WE used to do the >same thing? "The same thing", in the above, is *UN*mapping page 0, so that attempts to dereference NULL pointers get SIGSEGV - *NOT* mapping page 0 such that programs that attempt to dereference NULL pointers don't get SIGSEGV - which indicates that: >Remember all of the programs that used to work before NetBSD and FreeBSD >unmapped page 0???? if "WE" means "{Net,Free}BSD", then "WE" used *NOT* to do the same thing, and now *DO* the same thing, i.e. (quite properly) punish programs that don't check for NULL pointers.