3.2.64-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Honig <aho...@google.com>

commit 2febc839133280d5a5e8e1179c94ea674489dae2 upstream.

There's a race condition in the PIT emulation code in KVM.  In
__kvm_migrate_pit_timer the pit_timer object is accessed without
synchronization.  If the race condition occurs at the wrong time this
can crash the host kernel.

This fixes CVE-2014-3611.

Signed-off-by: Andrew Honig <aho...@google.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 arch/x86/kvm/i8254.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -264,8 +264,10 @@ void __kvm_migrate_pit_timer(struct kvm_
                return;
 
        timer = &pit->pit_state.pit_timer.timer;
+       mutex_lock(&pit->pit_state.lock);
        if (hrtimer_cancel(timer))
                hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
+       mutex_unlock(&pit->pit_state.lock);
 }
 
 static void destroy_pit_timer(struct kvm_pit *pit)

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