Date: Tue, 26 Apr 2011 10:48:53 +0100 From: Bruce Cran <bruce@cran.org.uk> To: RW <rwmaillists@googlemail.com> Cc: freebsd-questions@freebsd.org Subject: Re: Password theft from memory? Message-ID: <20110426104853.00005460@unknown> In-Reply-To: <20110425232908.4104e026@gumby.homeunix.com> References: <BANLkTimJWAxW_4OmoeBQrvDDLjD-5Vr5hQ@mail.gmail.com> <BANLkTin_S%2BBRWu79AH16tPdgZd%2BUgZQAzQ@mail.gmail.com> <20110425151846.0a5359fd@gumby.homeunix.com> <20110425151536.GA61425@stainmore> <BANLkTinvvWhEy_A5ao=XWTpQOSTX0Vm2_A@mail.gmail.com> <20110425175420.GA61811@stainmore> <20110425232908.4104e026@gumby.homeunix.com>
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On Mon, 25 Apr 2011 23:29:08 +0100 RW <rwmaillists@googlemail.com> wrote: > The reason I thought that heap memory isn't zeroed is from the > discussion of pre-zeroed pages in this article: There's an idlezero task that runs by default (via the vm.idlezero_enable sysctl), zeroing unused pages, but malloc itself doesn't zero memory on demand by default. If you enable the 'Z' malloc.conf(3) option it does, though: Z Each byte of new memory allocated by malloc(), realloc() or reallocf() will be initialized to 0. Note that this initializa- tion only happens once for each byte, so realloc() and reallocf() calls do not zero memory that was previously allocated. This is intended for debugging and will impact performance negatively. -- Bruce Cran
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