From patchwork Tue Feb 18 18:12:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 11389225 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 992E417F0 for ; Tue, 18 Feb 2020 18:12:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 83DEC24649 for ; Tue, 18 Feb 2020 18:12:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726734AbgBRSMu (ORCPT ); Tue, 18 Feb 2020 13:12:50 -0500 Received: from foss.arm.com ([217.140.110.172]:57990 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726770AbgBRSMu (ORCPT ); Tue, 18 Feb 2020 13:12:50 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9FE9D101E; Tue, 18 Feb 2020 10:12:49 -0800 (PST) Received: from e121345-lin.cambridge.arm.com (e121345-lin.cambridge.arm.com [10.1.196.37]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 82C723F73B; Tue, 18 Feb 2020 10:12:48 -0800 (PST) From: Robin Murphy To: joro@8bytes.org, robdclark@gmail.com Cc: iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, stephan@gerhold.net, linux-arm-msm@vger.kernel.org, Brian Masney , Naresh Kamboju Subject: [PATCH] iommu/qcom: Fix bogus detach logic Date: Tue, 18 Feb 2020 18:12:41 +0000 Message-Id: X-Mailer: git-send-email 2.23.0.dirty MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Currently, the implementation of qcom_iommu_domain_free() is guaranteed to do one of two things: WARN() and leak everything, or dereference NULL and crash. That alone is terrible, but in fact the whole idea of trying to track the liveness of a domain via the qcom_domain->iommu pointer as a sanity check is full of fundamentally flawed assumptions. Make things robust and actually functional by not trying to be quite so clever. Reported-by: Brian Masney Tested-by: Brian Masney Reported-by: Naresh Kamboju Fixes: 0ae349a0f33f ("iommu/qcom: Add qcom_iommu") Signed-off-by: Robin Murphy Tested-by: Stephan Gerhold --- drivers/iommu/qcom_iommu.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-) diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c index 39759db4f003..4328da0b0a9f 100644 --- a/drivers/iommu/qcom_iommu.c +++ b/drivers/iommu/qcom_iommu.c @@ -344,21 +344,19 @@ static void qcom_iommu_domain_free(struct iommu_domain *domain) { struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain); - if (WARN_ON(qcom_domain->iommu)) /* forgot to detach? */ - return; - iommu_put_dma_cookie(domain); - /* NOTE: unmap can be called after client device is powered off, - * for example, with GPUs or anything involving dma-buf. So we - * cannot rely on the device_link. Make sure the IOMMU is on to - * avoid unclocked accesses in the TLB inv path: - */ - pm_runtime_get_sync(qcom_domain->iommu->dev); - - free_io_pgtable_ops(qcom_domain->pgtbl_ops); - - pm_runtime_put_sync(qcom_domain->iommu->dev); + if (qcom_domain->iommu) { + /* + * NOTE: unmap can be called after client device is powered + * off, for example, with GPUs or anything involving dma-buf. + * So we cannot rely on the device_link. Make sure the IOMMU + * is on to avoid unclocked accesses in the TLB inv path: + */ + pm_runtime_get_sync(qcom_domain->iommu->dev); + free_io_pgtable_ops(qcom_domain->pgtbl_ops); + pm_runtime_put_sync(qcom_domain->iommu->dev); + } kfree(qcom_domain); } @@ -404,7 +402,7 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain); unsigned i; - if (!qcom_domain->iommu) + if (WARN_ON(!qcom_domain->iommu)) return; pm_runtime_get_sync(qcom_iommu->dev); @@ -417,8 +415,6 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de ctx->domain = NULL; } pm_runtime_put_sync(qcom_iommu->dev); - - qcom_domain->iommu = NULL; } static int qcom_iommu_map(struct iommu_domain *domain, unsigned long iova,