Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754545AbaKKL5z (ORCPT ); Tue, 11 Nov 2014 06:57:55 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:57342 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753799AbaKKLJs (ORCPT ); Tue, 11 Nov 2014 06:09:48 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Andrew Honig , Paolo Bonzini , Luis Henriques Subject: [PATCH 3.16.y-ckt 050/170] KVM: x86: Improve thread safety in pit Date: Tue, 11 Nov 2014 11:06:49 +0000 Message-Id: <1415704129-12709-51-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> References: <1415704129-12709-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.7-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Honig commit 2febc839133280d5a5e8e1179c94ea674489dae2 upstream. There's a race condition in the PIT emulation code in KVM. In __kvm_migrate_pit_timer the pit_timer object is accessed without synchronization. If the race condition occurs at the wrong time this can crash the host kernel. This fixes CVE-2014-3611. Signed-off-by: Andrew Honig Signed-off-by: Paolo Bonzini Signed-off-by: Luis Henriques --- arch/x86/kvm/i8254.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c index 518d86471b76..298781d4cfb4 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -262,8 +262,10 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu) return; timer = &pit->pit_state.timer; + mutex_lock(&pit->pit_state.lock); if (hrtimer_cancel(timer)) hrtimer_start_expires(timer, HRTIMER_MODE_ABS); + mutex_unlock(&pit->pit_state.lock); } static void destroy_pit_timer(struct kvm_pit *pit) -- 2.1.0 -- 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/