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Date: Fri, 12 Aug 2016 08:01:31 +0200 (CEST)
From: Jiri Kosina <jikos@...nel.org>
To: Thomas Garnier <thgarnie@...gle.com>
cc: "Rafael J . Wysocki" <rjw@...ysocki.net>, Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, keescook@...omium.org,
kernel-hardening@...ts.openwall.com, bpetkov@...e.de, yinghai@...nel.org
Subject: Re: [PATCH v1] x86/power/64: Restore processor state before using
per-cpu variables
On Thu, 11 Aug 2016, Thomas Garnier wrote:
> Restore the processor state before calling any other function to ensure
> per-cpu variables can be used with KASLR memory randomization.
>
> Tracing functions use per-cpu variables (gs based) and one was called
> just before restoring the processor state fully. It resulted in a double
> fault when both the tracing & the exception handler functions tried to
> use a per-cpu variable.
>
> Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
Alright, this did the trick, thanks :) Feel free to add
Reported-by: Jiri Kosina <jkosina@...e.cz>
Tested-by: Jiri Kosina <jkosina@...e.cz>
One thing is still beyond me though ... how the heck this doesn't happen
without DEBUG_LOCK_ALLOC? The percpu area pointer should be corrupted
nevertheless, shouldn't it?
Thanks,
--
Jiri Kosina
SUSE Labs
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