| From | Ben Hutchings <> | Date | Sat, 01 Nov 2014 22:28:03 +0000 | Subject | [PATCH 3.2 086/102] KVM: x86: Improve thread safety in pit |
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3.2.64-rc1 review patch. If anyone has any objections, please let me know.
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From: Andy Honig <ahonig@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 <ahonig@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@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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