Messages in this thread Patch in this message | | | From | Thomas Garnier <> | Subject | [PATCH v2] x86/power/64: Restore processor state before using per-cpu variables | Date | Fri, 12 Aug 2016 10:52:44 -0700 |
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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.
Reported-by: Jiri Kosina <jkosina@suse.cz> Tested-by: Jiri Kosina <jkosina@suse.cz> Acked-by: Pavel Machek <pavel@ucw.cz> Reported-and-tested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Thomas Garnier <thgarnie@google.com> --- Based on next-20160808
Thanks to Rafael, Jiri & Borislav in tracking down this bug and help testing this fix. --- 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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