linux-kernel - Re: [PATCH v3] x86/power/64: Fix kernel text mapping corruption during image restoration

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Date:	Thu, 30 Jun 2016 04:20:43 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Logan Gunthorpe <logang@...tatee.com>
Cc:	Kees Cook <keescook@...omium.org>, Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	lkml <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Andy Lutomirski <luto@...nel.org>,
	Brian Gerst <brgerst@...il.com>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Stephen Smalley <sds@...ho.nsa.gov>
Subject: Re: [PATCH v3] x86/power/64: Fix kernel text mapping corruption during image restoration

On Wednesday, June 29, 2016 07:52:18 PM Logan Gunthorpe wrote:
> Hey Raf,
> 
> Sorry to report that although the patch works the majority of the time, 
> I just got a suspicious kernel panic during resume.
> 
> It said:
> 
> "kernel tried to execute NX protected page - exploit attempt? (uid: 0)"
> 
> You can find a photo of the panic here:
> 
> http://staff.deltatee.com/~logang/panic.jpg

Thanks for the report!

That's not what Boris was seeing at least.

It looks like clearing the NX bit for relocated_restore_code in
relocate_restore_code() didn't work for some reason.

I don't see why it may not work ATM, I need to have a fresh look at that
tomorrow.

I had hoped to be able to fix this bug for 4.7, but it looks like it will
miss the mark after all.  Oh well.

Thanks,
Rafael