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Commit 1e8ba6fb authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
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[PATCH] kvm: fix vcpu freeing bug 



vcpu_load() can return NULL and it sometimes does in failure paths (for
example when the userspace ABI version is too old) - causing a preemption
count underflow in the ->vcpu_free() later on.  So check for NULL.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8cd13307

drivers/kvm/kvm_main.c

+3 −1
Original line number Diff line number Diff line
@@ -272,7 +272,9 @@ static void kvm_free_physmem(struct kvm *kvm) 


static void kvm_free_vcpu(struct kvm_vcpu *vcpu)

{

	vcpu_load(vcpu->kvm, vcpu_slot(vcpu));

	if (!vcpu_load(vcpu->kvm, vcpu_slot(vcpu)))

		return;



	kvm_mmu_destroy(vcpu);

	vcpu_put(vcpu);

	kvm_arch_ops->vcpu_free(vcpu);