Date: Tue, 20 Jul 1999 10:29:09 -0700 (PDT) From: David Wolfskill <dhw@whistle.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: RE: Overcommit and calloc() Message-ID: <199907201729.KAA50728@pau-amma.whistle.com> In-Reply-To: <005101bed2d5$433a16e0$291c453f@kbyanc.alcnet.com>
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>From: "Kelly Yancey" <kbyanc@alcnet.com> >Date: Tue, 20 Jul 1999 13:28:21 -0400 > On recent thought though, I seem to recall having read in the 4.4BSD >Daemon book that having the kernel zero memory is not the preferred >practice, but present because when they tried to stop many progrems dies >which assumed memory was initialized to zero. If I am remembering that >correctly, then, the only real concern is that one day we may want to kernel >to stop zeroing pages, in which case the extra logic in calloc() would be >for nought. I'd *think* you'd want to ensure that lack of initializing the data didn't become a way for unintended access to data that should not have been available to the process in question. (Ugh. Too many negatives in there.) Anyway, the process merely reminded me of the ability on a system I used 28+ years ago, where a FORTRAN program could open a file for writing, but read it first... and possibly find some "interesting" information left over from a previous program.... (No, that wasn't a UNIX system, let alone FreeBSD. :-}) Cheers, david -- David Wolfskill dhw@whistle.com UNIX System Administrator voice: (650) 577-7158 pager: (888) 347-0197 FAX: (650) 372-5915 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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