linux-kernel - Re: [PATCH v1 0/2] x86/power/64: Make KASLR memory randomization compatible with hibernation

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Message-ID: <6770834.oEI2u9Z85J@vostro.rjw.lan>
Date:	Tue, 02 Aug 2016 01:48:13 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Thomas Garnier <thgarnie@...gle.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Kees Cook <keescook@...omium.org>,
	Yinghai Lu <yinghai@...nel.org>, Pavel Machek <pavel@....cz>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v1 0/2] x86/power/64: Make KASLR memory randomization compatible with hibernation

On Monday, August 01, 2016 10:07:58 AM Thomas Garnier wrote:
> ***Background:
> KASLR memory randomization for x86_64 was added when KASLR did not support hibernation. Now that it does, some changes are needed.
> 
> ***Problems that needed solving:
> Hibernation was failing on reboot with a GP fault when CONFIG_RANDOMIZE_MEMORY was enabled. Two issues were identified.
> 
> The original fault was due to a wrong physical address assigned to cr3. The problem was introduced with __PAGE_OFFSET becoming a global variable when randomized. The fix uses a define to use the glbobal or immediate value based on config settings.
> 
> The second isssue was that the temporary page table mapping did not support virtual addresses not aligned on PGD level. KASLR memory randomization will generated a random address aligned on PUD level. The fix correctly calculates the offset on all levels of the temporary page table.
> 
> ***Parts:
>  - 01/02: Support unaligned addresses (second issue)
>  - 02/02: Fix __PAGE_OFFSET usage on assembly (first issue)

Thanks a lot for taking care of this!

Patch [2/2] looks good to me, but I'd to the [1/2] differently (more details
will follow).

Thanks,
Rafael