Commit bd768e14 authored Oct 21, 2016 by Ido Yariv Committed by Paolo Bonzini Oct 28, 2016

KVM: x86: fix wbinvd_dirty_mask use-after-free



vcpu->arch.wbinvd_dirty_mask may still be used after freeing it,
corrupting memory. For example, the following call trace may set a bit
in an already freed cpu mask:
    kvm_arch_vcpu_load
    vcpu_load
    vmx_free_vcpu_nested
    vmx_free_vcpu
    kvm_arch_vcpu_free

Fix this by deferring freeing of wbinvd_dirty_mask.

Cc: stable@vger.kernel.org
Signed-off-by: Ido Yariv <ido@wizery.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

parent 796f4687

arch/x86/kvm/x86.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -7410,10 +7410,12 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)

		void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
		{
		void *wbinvd_dirty_mask = vcpu->arch.wbinvd_dirty_mask;

		kvmclock_reset(vcpu);

		free_cpumask_var(vcpu->arch.wbinvd_dirty_mask);
		kvm_x86_ops->vcpu_free(vcpu);
		free_cpumask_var(wbinvd_dirty_mask);
		}

		struct kvm_vcpu kvm_arch_vcpu_create(struct kvm kvm,

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