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Date: Wed, 27 Jun 2007 00:11:38 -0400 From: Rik van Riel <riel@...hat.com> To: Ulrich Drepper <drepper@...il.com> CC: Davide Libenzi <davidel@...ilserver.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [patch 2/3] MAP_NOZERO - implement sys_brk2() Ulrich Drepper wrote: > On 6/26/07, Rik van Riel <riel@...hat.com> wrote: >> Since programs can get back free()d memory after a malloc(), >> with the old contents of the memory intact, surely your >> MAP_NONZERO behavior could be the default for programs that >> can get away with it? >> >> Maybe we could use some magic ELF header, similar to the >> way non-executable stack is handled? > > No. This is an implementation detail of the libc version. The malloc > as compiled today is expecting brk-ed memory to be zeroed. This > default can of course be changed (it's a simple define) but you cannot > make this the default behavior for brk. After going through the first malloc()/free() cycle, surely the memory will no longer be zeroed on the second malloc() ? What makes the first brk malloc so special? -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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