From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934163AbbA1EVR (ORCPT ); Tue, 27 Jan 2015 23:21:17 -0500 Received: from mail.kernel.org ([198.145.29.136]:39495 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933188AbbA1EVM (ORCPT ); Tue, 27 Jan 2015 23:21:12 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andy Honig , Paolo Bonzini , Zefan Li Subject: [PATCH 3.4 079/177] KVM: x86: Improve thread safety in pit Date: Wed, 28 Jan 2015 12:08:44 +0800 Message-Id: <1422418236-12852-157-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Honig 3.4.106-rc1 review patch. If anyone has any objections, please let me know. ------------------ 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 [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li --- 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 d68f99d..db336f9 100644 --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -263,8 +263,10 @@ void __kvm_migrate_pit_timer(struct kvm_vcpu *vcpu) return; timer = &pit->pit_state.pit_timer.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) -- 1.9.1