Bugzilla: 1042081 Upstream-status: 3.13 and sent for stable Delivered-To: jwboyer@gmail.com Received: by 10.76.104.107 with SMTP id gd11csp361402oab; Thu, 12 Dec 2013 12:43:43 -0800 (PST) X-Received: by 10.68.241.134 with SMTP id wi6mr15423072pbc.44.1386881023599; Thu, 12 Dec 2013 12:43:43 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id w3si17375457pbh.89.2013.12.12.12.43.07 for ; Thu, 12 Dec 2013 12:43:43 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mail=linux-kernel-owner@vger.kernel.org; dkim=neutral (bad format) header.i=@gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752145Ab3LLUiu (ORCPT + 99 others); Thu, 12 Dec 2013 15:38:50 -0500 Received: from mail-ee0-f45.google.com ([74.125.83.45]:47138 "EHLO mail-ee0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751902Ab3LLUhP (ORCPT ); Thu, 12 Dec 2013 15:37:15 -0500 Received: by mail-ee0-f45.google.com with SMTP id d49so478739eek.32 for ; Thu, 12 Dec 2013 12:37:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:date:message-id; bh=Fa9qXXe9oER+jgB6WXA5v2LyR8O2Vaag7ZsOsv67MLg=; b=WbBUzKN8o3OzB75st3w60z/rVczWaaxrvWc2URlwJwZ0lgqObvbXvAb3ophFJxsr/O P3rEj33CGt5vFAmZWsrST8I4pVb7IPZYqmPuBklMhDmvegy2um2xEDCyIuI0oybwgple n1dYPBTNqBhiiLgIUeKgEf88yU5dsAgKOZSTnkMYhDSy9pnGxRda4WtErJ+SHjvcMaX3 t2Vt97egJ2n+e+2BvnpS8xZ8biqp6/l3EzvdsL4W849fUUshAKva4Npu0T/D4E3JIp2O 3uY+geb/txJL2rOCacT3RljUb3+zAy2zhqGSjKR3AHePFNIX9RxfMi/vlPmTjO0vfmCP H86Q== X-Received: by 10.14.2.73 with SMTP id 49mr10139590eee.15.1386880633625; Thu, 12 Dec 2013 12:37:13 -0800 (PST) Received: from playground.com (net-2-35-202-54.cust.dsl.vodafone.it. [2.35.202.54]) by mx.google.com with ESMTPSA id o47sm70323739eem.21.2013.12.12.12.37.11 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Dec 2013 12:37:12 -0800 (PST) From: Paolo Bonzini To: linux-kernel@vger.kernel.org Cc: gleb@redhat.com, kvm@vger.kernel.org, pmatouse@redhat.com, Andy Honig , stable@vger.kernel.org Subject: [PATCH] KVM: x86: Fix potential divide by 0 in lapic (CVE-2013-6367) Date: Thu, 12 Dec 2013 21:36:52 +0100 Message-Id: <1386880614-23300-2-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Honig Under guest controllable circumstances apic_get_tmcct will execute a divide by zero and cause a crash. If the guest cpuid support tsc deadline timers and performs the following sequence of requests the host will crash. - Set the mode to periodic - Set the TMICT to 0 - Set the mode bits to 11 (neither periodic, nor one shot, nor tsc deadline) - Set the TMICT to non-zero. Then the lapic_timer.period will be 0, but the TMICT will not be. If the guest then reads from the TMCCT then the host will perform a divide by 0. This patch ensures that if the lapic_timer.period is 0, then the division does not occur. Reported-by: Andrew Honig Cc: stable@vger.kernel.org Signed-off-by: Andrew Honig Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 5439117d5c4c..89b52ec7d09c 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -841,7 +841,8 @@ static u32 apic_get_tmcct(struct kvm_lapic *apic) ASSERT(apic != NULL); /* if initial count is 0, current count should also be 0 */ - if (kvm_apic_get_reg(apic, APIC_TMICT) == 0) + if (kvm_apic_get_reg(apic, APIC_TMICT) == 0 || + apic->lapic_timer.period == 0) return 0; remaining = hrtimer_get_remaining(&apic->lapic_timer.timer); -- 1.8.3.1 -- 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/