From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacob Pan Subject: Re: iommu/vt-d: drop mm use count if address is not canonical Date: Fri, 26 Apr 2019 08:47:31 -0700 Message-ID: <20190426084731.7481d384@jacob-builder> References: <1555492377-79859-1-git-send-email-bianpan2016@163.com> <20190426133846.GC24576@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190426133846.GC24576@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org To: Joerg Roedel Cc: Pan Bian , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Woodhouse , jacob.jun.pan@linux.intel.com List-Id: iommu@lists.linux-foundation.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] 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,URIBL_BLOCKED autolearn=unavailable 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 67D1EC43218 for ; Fri, 26 Apr 2019 15:47:54 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3A461205ED for ; Fri, 26 Apr 2019 15:47:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A461205ED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id EB48028CF; Fri, 26 Apr 2019 15:47:53 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id DF56B2738 for ; Fri, 26 Apr 2019 15:44:48 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 7C02382A for ; Fri, 26 Apr 2019 15:44:48 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Apr 2019 08:44:48 -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 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 Cc: Pan Bian , David Woodhouse , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Message-ID: <20190426154731.bO31G6Z2eeDbtbs_jyZuaU7XPWPYc73F0-t42iwBz54@z> 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] _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu