Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932128AbbGASs0 (ORCPT ); Wed, 1 Jul 2015 14:48:26 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44982 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753836AbbGASlH (ORCPT ); Wed, 1 Jul 2015 14:41:07 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Marc Zyngier , Christoffer Dall , Shannon Zhao Subject: [PATCH 3.14 19/34] KVM: ARM: vgic: plug irq injection race Date: Wed, 1 Jul 2015 11:40:26 -0700 Message-Id: <20150701183956.042847505@linuxfoundation.org> X-Mailer: git-send-email 2.4.4 In-Reply-To: <20150701183955.306219425@linuxfoundation.org> References: <20150701183955.306219425@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1836 Lines: 50 3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Zyngier commit 71afaba4a2e98bb7bdeba5078370ab43d46e67a1 upstream. [Since we don't backport commit 227844f (arm/arm64: KVM: Rename irq_state to irq_pending) for linux-3.14.y, here we still use vgic_update_irq_state instead of vgic_update_irq_pending.] As it stands, nothing prevents userspace from injecting an interrupt before the guest's GIC is actually initialized. This goes unnoticed so far (as everything is pretty much statically allocated), but ends up exploding in a spectacular way once we switch to a more dynamic allocation (the GIC data structure isn't there yet). The fix is to test for the "ready" flag in the VGIC distributor before trying to inject the interrupt. Note that in order to avoid breaking userspace, we have to ignore what is essentially an error. Signed-off-by: Marc Zyngier Acked-by: Christoffer Dall Signed-off-by: Shannon Zhao Signed-off-by: Greg Kroah-Hartman --- virt/kvm/arm/vgic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -1387,7 +1387,8 @@ out: int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num, bool level) { - if (vgic_update_irq_state(kvm, cpuid, irq_num, level)) + if (likely(vgic_initialized(kvm)) && + vgic_update_irq_state(kvm, cpuid, irq_num, level)) vgic_kick_vcpus(kvm); return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/