35 lines
1.1 KiB
Diff
35 lines
1.1 KiB
Diff
From: Andy Honig <ahonig@google.com>
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Date: Wed, 27 Aug 2014 14:42:54 -0700
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Subject: KVM: x86: Improve thread safety in pit
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Origin: https://git.kernel.org/linus/2febc839133280d5a5e8e1179c94ea674489dae2
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There's a race condition in the PIT emulation code in KVM. In
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__kvm_migrate_pit_timer the pit_timer object is accessed without
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synchronization. If the race condition occurs at the wrong time this
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can crash the host kernel.
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This fixes CVE-2014-3611.
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Cc: stable@vger.kernel.org
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Signed-off-by: Andrew Honig <ahonig@google.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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---
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arch/x86/kvm/i8254.c | 2 ++
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1 file changed, 2 insertions(+)
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diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
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index 518d864..298781d 100644
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--- a/arch/x86/kvm/i8254.c
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+++ b/arch/x86/kvm/i8254.c
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@@ -262,8 +262,10 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu)
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return;
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timer = &pit->pit_state.timer;
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+ mutex_lock(&pit->pit_state.lock);
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if (hrtimer_cancel(timer))
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hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
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+ mutex_unlock(&pit->pit_state.lock);
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}
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static void destroy_pit_timer(struct kvm_pit *pit)
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