Date: Sat, 11 Jun 2005 13:12:11 +0200 From: des@des.no (=?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?=) To: Mike Hunter <mhunter@ack.berkeley.edu> Cc: freebsd-hackers@freebsd.org Subject: Re: unitialized memory is all zeros...why not garbage instead? Message-ID: <86vf4lb110.fsf@xps.des.no> In-Reply-To: <20050610224058.GA11336@malcolm.berkeley.edu> (Mike Hunter's message of "Fri, 10 Jun 2005 15:40:58 -0700") References: <20050610224058.GA11336@malcolm.berkeley.edu>
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Mike Hunter <mhunter@ack.berkeley.edu> writes: > I have a feeling that I'm missing something really obvious, but I'm having > trouble understanding why the following program: > [...] > Never prints anything but "0"'s. Because the kernel always hands processes pre-zeroed pages. > I ran less up to my hw.physmem by feeding it /dev/random and watching > top, and then ran the program, so I "know" there was tons of non-zero > bits in memory. If your program had been able to see leftovers from less in its own address space, we'd have a huge security hole on our hands. > I'm curious because I am worried about information leaks between processes > on the same machine...did somebody decide to solve this problem while I > wasn't paying attention? :) It's always been this way. DES --=20 Dag-Erling Sm=F8rgrav - des@des.no
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