From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 220B4C43218 for ; Fri, 26 Apr 2019 15:44:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE819208CA for ; Fri, 26 Apr 2019 15:44:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726474AbfDZPos (ORCPT ); Fri, 26 Apr 2019 11:44:48 -0400 Received: from mga04.intel.com ([192.55.52.120]:32277 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726255AbfDZPos (ORCPT ); Fri, 26 Apr 2019 11:44:48 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Apr 2019 08:44:47 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,398,1549958400"; d="scan'208";a="139087744" Received: from jacob-builder.jf.intel.com (HELO jacob-builder) ([10.7.199.155]) by orsmga006.jf.intel.com with ESMTP; 26 Apr 2019 08:44:47 -0700 Date: Fri, 26 Apr 2019 08:47:31 -0700 From: Jacob Pan To: Joerg Roedel Cc: Pan Bian , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Woodhouse , jacob.jun.pan@linux.intel.com Subject: Re: iommu/vt-d: drop mm use count if address is not canonical Message-ID: <20190426084731.7481d384@jacob-builder> In-Reply-To: <20190426133846.GC24576@8bytes.org> References: <1555492377-79859-1-git-send-email-bianpan2016@163.com> <20190426133846.GC24576@8bytes.org> Organization: OTC X-Mailer: Claws Mail 3.13.2 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 26 Apr 2019 15:38:46 +0200 Joerg Roedel wrote: > [ Adding more people. ] > > On Wed, Apr 17, 2019 at 05:12:57PM +0800, Pan Bian wrote: > > The use count of svm->mm is incremented by mmget_not_zero. However, > > it is not dropped when the address is not canonical. This patch > > fixes the bug. > > > > Fixes: 9d8c3af31607("iommu/vt-d: IOMMU Page Request needs to check > > if address is canonical.") > > > > Signed-off-by: Pan Bian > > --- > > drivers/iommu/intel-svm.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > > index 3a4b09a..2630d2e 100644 > > --- a/drivers/iommu/intel-svm.c > > +++ b/drivers/iommu/intel-svm.c > > @@ -574,8 +574,10 @@ static irqreturn_t prq_event_thread(int irq, > > void *d) goto bad_req; > > > > /* If address is not canonical, return invalid > > response */ > > - if (!is_canonical_address(address)) > > + if (!is_canonical_address(address)) { > > + mmput(svm->mm); > > goto bad_req; > > + } > > > > down_read(&svm->mm->mmap_sem); > > vma = find_extend_vma(svm->mm, address); > > I think it is better to move the canonical address check before > mmget_not_zero() like in the diff below. But I let David and Jacob > comment on this. > Looks good to me. Tested with PRQ and fake non canonical address then send an invalid page response. Tested-by: Jacob Pan > Regards, > > Joerg > > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c > index 8f87304f915c..5e9e1eee8336 100644 > --- a/drivers/iommu/intel-svm.c > +++ b/drivers/iommu/intel-svm.c > @@ -586,14 +586,15 @@ static irqreturn_t prq_event_thread(int irq, > void *d) > * any faults on kernel addresses. */ > if (!svm->mm) > goto bad_req; > - /* If the mm is already defunct, don't handle > faults. */ > - if (!mmget_not_zero(svm->mm)) > - goto bad_req; > > /* If address is not canonical, return invalid > response */ if (!is_canonical_address(address)) > goto bad_req; > > + /* If the mm is already defunct, don't handle > faults. */ > + if (!mmget_not_zero(svm->mm)) > + goto bad_req; > + > down_read(&svm->mm->mmap_sem); > vma = find_extend_vma(svm->mm, address); > if (!vma || address < vma->vm_start) [Jacob Pan]