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[142.68.128.5]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-46e104026c3sm42918831cf.60.2025.01.20.06.37.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jan 2025 06:37:20 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1tZstz-00000003PsB-2WHL; Mon, 20 Jan 2025 10:37:19 -0400 Date: Mon, 20 Jan 2025 10:37:19 -0400 From: Jason Gunthorpe To: Nicolin Chen Cc: kevin.tian@intel.com, baolu.lu@linux.intel.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH rc v2] iommufd: Explicitize struct iommu_hwpt_pgfault padding Message-ID: <20250120143719.GN674319@ziepe.ca> References: <20250120062411.1589-1-nicolinc@nvidia.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250120062411.1589-1-nicolinc@nvidia.com> On Sun, Jan 19, 2025 at 10:24:11PM -0800, Nicolin Chen wrote: > --- a/drivers/iommu/iommufd/fault.c > +++ b/drivers/iommu/iommufd/fault.c > @@ -253,6 +253,7 @@ static void iommufd_compose_fault_message(struct iommu_fault *fault, > hwpt_fault->pasid = fault->prm.pasid; > hwpt_fault->grpid = fault->prm.grpid; > hwpt_fault->perm = fault->prm.perm; > + hwpt_fault->__reserved = 0; > hwpt_fault->addr = fault->prm.addr; > hwpt_fault->length = 0; > hwpt_fault->cookie = cookie; Yikes, so it was leaking kernel stack memory through the padding too. We should zero init the stack struct to be safe: @@ -247,7 +247,7 @@ static ssize_t iommufd_fault_fops_read(struct file *filep, char __user *buf, { size_t fault_size = sizeof(struct iommu_hwpt_pgfault); struct iommufd_fault *fault = filep->private_data; - struct iommu_hwpt_pgfault data; + struct iommu_hwpt_pgfault data = {}; struct iommufd_device *idev; struct iopf_group *group; struct iopf_fault *iopf; I can fix it up if that is the only change Jason