Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964985AbdCJJec (ORCPT ); Fri, 10 Mar 2017 04:34:32 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:42716 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935569AbdCJJe3 (ORCPT ); Fri, 10 Mar 2017 04:34:29 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vitaly Kuznetsov , "K. Y. Srinivasan" Subject: [PATCH 4.10 123/167] hv: dont reset hv_context.tsc_page on crash Date: Fri, 10 Mar 2017 10:09:26 +0100 Message-Id: <20170310084003.424637882@linuxfoundation.org> X-Mailer: git-send-email 2.12.0 In-Reply-To: <20170310083956.767605269@linuxfoundation.org> References: <20170310083956.767605269@linuxfoundation.org> User-Agent: quilt/0.65 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: 1030 Lines: 37 4.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vitaly Kuznetsov commit 56ef6718a1d8d77745033c5291e025ce18504159 upstream. It may happen that secondary CPUs are still alive and resetting hv_context.tsc_page will cause a consequent crash in read_hv_clock_tsc() as we don't check for it being not NULL there. It is safe as we're not freeing this page anyways. Signed-off-by: Vitaly Kuznetsov Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/hv.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -309,9 +309,10 @@ void hv_cleanup(bool crash) hypercall_msr.as_uint64 = 0; wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64); - if (!crash) + if (!crash) { vfree(hv_context.tsc_page); - hv_context.tsc_page = NULL; + hv_context.tsc_page = NULL; + } } #endif }