From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754395AbeCGMUx (ORCPT ); Wed, 7 Mar 2018 07:20:53 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:49608 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754345AbeCGMUu (ORCPT ); Wed, 7 Mar 2018 07:20:50 -0500 Subject: Re: [PATCH v8 1/5] iommu/arm-smmu: Destroy domain context in failure path To: Vivek Gautam , joro@8bytes.org, robh+dt@kernel.org, mark.rutland@arm.com, rjw@rjwysocki.net, will.deacon@arm.com, robdclark@gmail.com, iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Cc: tfiga@chromium.org, jcrouse@codeaurora.org, sboyd@codeaurora.org, sricharan@codeaurora.org, m.szyprowski@samsung.com, architt@codeaurora.org, linux-arm-msm@vger.kernel.org References: <20180302101050.6191-1-vivek.gautam@codeaurora.org> <20180302101050.6191-2-vivek.gautam@codeaurora.org> From: Robin Murphy Message-ID: Date: Wed, 7 Mar 2018 12:20:45 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20180302101050.6191-2-vivek.gautam@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/03/18 10:10, Vivek Gautam wrote: > If we fail after initializing domain_context, we should destroy > the context to free up resources. Have another think about why the "problem" this patch caters for cannot ever happen (hint: consider how domain->smmu is used in arm_smmu_init_domain_context()). And then also about the really catastrophically bad problem it actually introduces (hint: "iommu_attach(domain, good_dev); iommu_attach(domain, bad_dev);") Robin. > Signed-off-by: Vivek Gautam > --- > > * New patch added in this series. > > drivers/iommu/arm-smmu.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 69e7c60792a8..ffc152c36002 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -1223,11 +1223,16 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) > dev_err(dev, > "cannot attach to SMMU %s whilst already attached to domain on SMMU %s\n", > dev_name(smmu_domain->smmu->dev), dev_name(smmu->dev)); > - return -EINVAL; > + ret = -EINVAL; > + goto destroy_domain; > } > > /* Looks ok, so add the device to the domain */ > return arm_smmu_domain_add_master(smmu_domain, fwspec); > + > +destroy_domain: > + arm_smmu_destroy_domain_context(domain); > + return ret; > } > > static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova, >