From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: iommu/vt-d: drop mm use count if address is not canonical Date: Fri, 26 Apr 2019 15:38:46 +0200 Message-ID: <20190426133846.GC24576@8bytes.org> References: <1555492377-79859-1-git-send-email-bianpan2016@163.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1555492377-79859-1-git-send-email-bianpan2016@163.com> Sender: linux-kernel-owner@vger.kernel.org To: Pan Bian Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Jacob Pan , David Woodhouse List-Id: iommu@lists.linux-foundation.org [ 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. 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) 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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 1E91DC43218 for ; Fri, 26 Apr 2019 13:41:22 +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 ED16A206E0 for ; Fri, 26 Apr 2019 13:41:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED16A206E0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org 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 6E4D627D6; Fri, 26 Apr 2019 13:41:21 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id E6B4127CE for ; Fri, 26 Apr 2019 13:38:50 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 71CC482A for ; Fri, 26 Apr 2019 13:38:50 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id AC762447; Fri, 26 Apr 2019 15:38:48 +0200 (CEST) Date: Fri, 26 Apr 2019 15:38:46 +0200 From: Joerg Roedel To: Pan Bian Subject: Re: iommu/vt-d: drop mm use count if address is not canonical Message-ID: <20190426133846.GC24576@8bytes.org> References: <1555492377-79859-1-git-send-email-bianpan2016@163.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1555492377-79859-1-git-send-email-bianpan2016@163.com> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: iommu@lists.linux-foundation.org, David Woodhouse , 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: <20190426133846.hdYSU74X-MnHTdE7O44EGieWGGiqHV7Tea3McDfc_PQ@z> [ 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. 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) _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu