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Date: Thu, 11 Aug 2016 14:49:29 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: "Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>
Cc: linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
keescook@...omium.org,
kernel-hardening@...ts.openwall.com,
jikos@...nel.org,
bpetkov@...e.de,
yinghai@...nel.org,
Thomas Garnier <thgarnie@...gle.com>
Subject: [PATCH v1] x86/power/64: Restore processor state before using per-cpu variables
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>
---
Based on next-20160808
Thanks to Rafael, Jiri & Borislav in tracking down this bug.
---
kernel/power/hibernate.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index a881c6a..33c79b6 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -300,12 +300,12 @@ static int create_image(int platform_mode)
save_processor_state();
trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true);
error = swsusp_arch_suspend();
+ /* Restore control flow magically appears here */
+ restore_processor_state();
trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false);
if (error)
printk(KERN_ERR "PM: Error %d creating hibernation image\n",
error);
- /* Restore control flow magically appears here */
- restore_processor_state();
if (!in_suspend)
events_check_enabled = false;
--
2.8.0.rc3.226.g39d4020
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