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[47.54.130.67]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-50e61c191basm249642351cf.16.2026.04.27.07.01.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Apr 2026 07:01:32 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1wHMWh-00000003XIx-3yuA; Mon, 27 Apr 2026 11:01:31 -0300 Date: Mon, 27 Apr 2026 11:01:31 -0300 From: Jason Gunthorpe To: Baolu Lu Cc: "Aneesh Kumar K.V (Arm)" , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Alexey Kardashevskiy , Bjorn Helgaas , Dan Williams , Joerg Roedel , Jonathan Cameron , Kevin Tian , Nicolin Chen , Samuel Ortiz , Steven Price , Suzuki K Poulose , Will Deacon , Xu Yilun , Shameer Kolothum Subject: Re: [PATCH v4 1/4] iommufd/device: Associate a kvm pointer to iommufd_device Message-ID: <20260427140131.GC740385@ziepe.ca> References: <20260427061005.901854-1-aneesh.kumar@kernel.org> <20260427061005.901854-2-aneesh.kumar@kernel.org> 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: On Mon, Apr 27, 2026 at 05:07:52PM +0800, Baolu Lu wrote: > iommufd_device_unbind() is an asynchronous teardown operation. Is it > possible for idev->kvm to persist or be accessed within the iommufd > subsystem after iommufd_device_unbind() has returned? Should we add the > change below to prevent this potential UAF case? > > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c > index 170a7005f0bc..dac39cb5e7cc 100644 > --- a/drivers/iommu/iommufd/device.c > +++ b/drivers/iommu/iommufd/device.c > @@ -333,6 +333,7 @@ EXPORT_SYMBOL_NS_GPL(iommufd_ctx_has_group, "IOMMUFD"); > */ > void iommufd_device_unbind(struct iommufd_device *idev) > { > + idev->kvm = NULL; > iommufd_object_destroy_user(idev->ictx, &idev->obj); > } > EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, "IOMMUFD"); iommufd_object_destroy_user() frees the memory of idev, it is not useful to null before free. Jason