Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753259AbaKAXA5 (ORCPT ); Sat, 1 Nov 2014 19:00:57 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60042 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751426AbaKAWj1 (ORCPT ); Sat, 1 Nov 2014 18:39:27 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Andy Honig" , "Paolo Bonzini" Date: Sat, 01 Nov 2014 22:28:03 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 086/102] KVM: x86: Improve thread safety in pit In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.64-rc1 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 [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- arch/x86/kvm/i8254.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kvm/i8254.c +++ b/arch/x86/kvm/i8254.c @@ -264,8 +264,10 @@ void __kvm_migrate_pit_timer(struct kvm_ 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) -- 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/