From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: [patch] KVM: fix vcpu freeing bug Date: Mon, 29 Jan 2007 19:46:12 +0100 Message-ID: <20070129184612.GA12235@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kvm-devel Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org From: Ingo Molnar Subject: [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: Ingo Molnar Index: linux/drivers/kvm/kvm_main.c =================================================================== --- linux.orig/drivers/kvm/kvm_main.c +++ linux/drivers/kvm/kvm_main.c @@ -357,7 +357,9 @@ static void kvm_free_physmem(struct 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); ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV