Date: Mon, 21 Aug 2017 11:39:15 +0100 From: Ard Biesheuvel <ard.biesheuvel@...aro.org> To: Mark Rutland <mark.rutland@....com> Cc: Kernel Hardening <kernel-hardening@...ts.openwall.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, Arnd Bergmann <arnd@...db.de>, Nicolas Pitre <nico@...aro.org>, Russell King <linux@...linux.org.uk>, Kees Cook <keescook@...omium.org>, Thomas Garnier <thgarnie@...gle.com>, Marc Zyngier <marc.zyngier@....com>, Tony Lindgren <tony@...mide.com>, Matt Fleming <matt@...eblueprint.co.uk>, Dave Martin <dave.martin@....com> Subject: Re: [PATCH 29/30] efi/libstub: arm: reserve bootloader supplied initrd in memory map On 21 August 2017 at 11:37, Mark Rutland <mark.rutland@....com> wrote: > On Mon, Aug 14, 2017 at 01:54:10PM +0100, Ard Biesheuvel wrote: >> Under KASLR, the EFI stub may allocate the kernel anywhere in the >> physical address space, which could be right on top of an initrd >> if it was supplied by the bootloader (i.e., GRUB) in /chosen rather >> than passed via the initrd= command line option. So allocate the >> pages explicitly, this ensures that the random memory allocation >> routine will disregard the region. > > I'm a little confused. Shouldn't the bootloader have allocated that > memory, leaving it reserved? > > If it hasn't, then that region could be allcoated by anything else at > any time (e.g. by the code which loads the kernel, or some EFI timer > callback), so that sounds like a bootloader bug that we can't fix. > Yeah, thinko on my part. Thanks for spotting that.
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