From d21225ee2b6fa9f7669526927f2e0bedebd90940 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Fri, 5 Jan 2007 16:36:59 -0800 Subject: [PATCH] [PATCH] KVM: Make loading cr3 more robust Prevent the guest's loading of a corrupt cr3 (pointing at no guest phsyical page) from crashing the host. Signed-off-by: Ingo Molnar Signed-off-by: Avi Kivity Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/kvm/kvm_main.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c index 0675d3e51692..67c1154960f0 100644 --- a/drivers/kvm/kvm_main.c +++ b/drivers/kvm/kvm_main.c @@ -463,7 +463,19 @@ void set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) vcpu->cr3 = cr3; spin_lock(&vcpu->kvm->lock); - vcpu->mmu.new_cr3(vcpu); + /* + * Does the new cr3 value map to physical memory? (Note, we + * catch an invalid cr3 even in real-mode, because it would + * cause trouble later on when we turn on paging anyway.) + * + * A real CPU would silently accept an invalid cr3 and would + * attempt to use it - with largely undefined (and often hard + * to debug) behavior on the guest side. + */ + if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT))) + inject_gp(vcpu); + else + vcpu->mmu.new_cr3(vcpu); spin_unlock(&vcpu->kvm->lock); } EXPORT_SYMBOL_GPL(set_cr3); -- 2.20.1