linux-kernel - [PATCH 5/4] KVM: x86: check bounds of APIC maps

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Date:	Thu, 27 Nov 2014 23:30:19 +0100
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	Gleb Natapov <gleb@...nel.org>,
	Nadav Amit <namit@...technion.ac.il>
Subject: [PATCH 5/4] KVM: x86: check bounds of APIC maps

They can't be violated now, but we think against the infinite thing.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 I realized it could make a separate patch as well,
 which might be more convenient.

 arch/x86/kvm/lapic.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 6c2b8a5..ae019f6 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -190,15 +190,16 @@ static void recalculate_apic_map(struct kvm *kvm)
 	kvm_for_each_vcpu(i, vcpu, kvm) {
 		struct kvm_lapic *apic = vcpu->arch.apic;
 		u16 cid, lid;
-		u32 ldr;
-
-		new->phys_map[kvm_apic_id(apic)] = apic;
+		u32 ldr, aid;
 
+		aid = kvm_apic_id(apic);
 		ldr = kvm_apic_get_reg(apic, APIC_LDR);
 		cid = apic_cluster_id(new, ldr);
 		lid = apic_logical_id(new, ldr);
 
-		if (lid)
+		if (aid < ARRAY_SIZE(new->phys_map))
+			new->phys_map[aid] = apic;
+		if (lid && cid < ARRAY_SIZE(new->logical_map))
 			new->logical_map[cid][ffs(lid) - 1] = apic;
 	}
 out:
-- 
2.1.0

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