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Commit 2febc839 authored by Andy Honig's avatar Andy Honig Committed by Paolo Bonzini
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KVM: x86: Improve thread safety in pit 



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.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarAndrew Honig <ahonig@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8b3c3104

arch/x86/kvm/i8254.c

+2 −0
Original line number Diff line number Diff line
@@ -262,8 +262,10 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu) 
		return;



	timer = &pit->pit_state.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)