Date: Mon, 25 Apr 2011 17:46:33 +0200 From: "C. P. Ghost" <cpghost@cordula.ws> To: freebsd-questions@freebsd.org Subject: Re: Password theft from memory? Message-ID: <BANLkTinvvWhEy_A5ao=XWTpQOSTX0Vm2_A@mail.gmail.com> In-Reply-To: <20110425151536.GA61425@stainmore> References: <BANLkTimJWAxW_4OmoeBQrvDDLjD-5Vr5hQ@mail.gmail.com> <BANLkTin_S%2BBRWu79AH16tPdgZd%2BUgZQAzQ@mail.gmail.com> <20110425151846.0a5359fd@gumby.homeunix.com> <20110425151536.GA61425@stainmore>
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On Mon, Apr 25, 2011 at 5:15 PM, Bob Hall <rjhjr0@gmail.com> wrote: > On Mon, Apr 25, 2011 at 03:18:46PM +0100, RW wrote: >> I don't believe the heap is allocated zeroed pages. =A0The kernel >> does allocate such pages to the BSS segment, but that's because it >> holds zeroed data such as C static variables. > > According to McKusick and Neville-Neil's book on FreeBSD, sbrk extends > the uninitialized data segment with zero-filled pages. Since malloc() is > an interface to sbrk, it does the same thing. True, except that malloc(3) now uses both sbrk(2) and mmap(2) allocators, depending on the user-settable flags in /etc/malloc.conf, MALLOC_OPTIONS and the global variable _malloc_options. So you have to look into mmap(2) too. -cpghost. --=20 Cordula's Web. http://www.cordula.ws/
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