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Thu, 8 Oct 2026 10:32:27 -0700 Received: from nvidia.com (10.127.8.9) by mail.nvidia.com (10.129.68.6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.49 via Frontend Transport; Thu, 8 Oct 2026 10:32:25 -0700 Date: Thu, 8 Oct 2026 10:32:23 -0700 From: Nicolin Chen To: Robin Murphy CC: "Peng Fan (OSS)" , Will Deacon , "Joerg Roedel (AMD)" , Jean-Philippe Brucker , Jason Gunthorpe , Thierry Reding , Krishna Reddy , "Jonathan Hunter" , , , , , Peng Fan Subject: Re: [PATCH RFC v5 2/6] iommu/arm-smmu-v3: Allocate streams individually Message-ID: References: <20261006-smmu-shared-sid-v5-0-169a59c671d3@nxp.com> <20261006-smmu-shared-sid-v5-2-169a59c671d3@nxp.com> <7626c1be-305e-478a-a017-548341d25419@arm.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <7626c1be-305e-478a-a017-548341d25419@arm.com> X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF0000A991:EE_|DM4PR12MB6206:EE_ X-MS-Office365-Filtering-Correlation-Id: 1a4f6afc-e8a3-4ba0-bab4-08df2562302c X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700016|7416014|376014|23010399003|82310400026|1800799024|4143699003|11063799006|10067099003|56012099006|18002099003|22082099003; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: T9Ua8oRnqjyMJR0UEoEIZmwLc27Z4hkekcuqtEVR1ApwyxOkcfav2weeIbioXt8hqqeoodNk0reUJOH/E+Ces7P5Kfgrah8itsISuuKxoakt2Iw1nV1aPJDoqf0R89DSNF2y7iTOBm7xvYQKxFUVfGvm2zhJonIz65z/43I0qxtGtFk+LGiqJwf6pr0Kho9mBpZ6IQqL5mtpnZWnC43FuJLi/8gY4vdN5MjsOdws7gpYgUPjfpD5OmU3Xwt8ydDXV0kSi3uVSTpRhS9UznigHcXvh+QBfG1qE4Iu1POZMC2I/odls082ptziL+M8QhoTl1GcrkHA6IyZ+kGo3UqYZc2N68CIl8zsGcKM6tD6PJrVU3G45YaFMykxwaVzFmURDgzRCbNUHL5++w5ifI/Lca95wOlPWVbutsLLwaDe3qUm0kwq0ZAXp5znY+j+QpV5 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 08 Oct 2026 17:32:55.3171 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 1a4f6afc-e8a3-4ba0-bab4-08df2562302c X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BN2PEPF0000A991.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB6206 On Thu, Oct 08, 2026 at 02:21:43PM +0100, Robin Murphy wrote: > On 08/10/2026 12:17 am, Nicolin Chen wrote: > > On Tue, Oct 06, 2026 at 08:19:08PM +0800, Peng Fan (OSS) wrote: > > > diff --git a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > > > index 6644075c1431e..bc62a3d5a63f9 100644 > > > --- a/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > > > +++ b/drivers/iommu/arm/arm-smmu-v3/tegra241-cmdqv.c > > > @@ -1257,7 +1257,7 @@ static int tegra241_vintf_init_vsid(struct iommufd_vdevice *vdev) > > > struct arm_smmu_master *master = dev_iommu_priv_get(dev); > > > struct tegra241_vintf *vintf = viommu_to_vintf(vdev->viommu); > > > struct tegra241_vintf_sid *vsid = vdev_to_vsid(vdev); > > > - struct arm_smmu_stream *stream = &master->streams[0]; > > > + struct arm_smmu_stream *stream = master->streams[0]; > > > > Sashiko raised a concern of an out-of-bounds pointer dereference. > > > > Though it's practically not possible, probably it would be safer > > to move this behind the check: > > > > if (master->num_streams != 1) > > return -EOPNOTSUPP; > > The IORT path unconditionally adds 1 ID via acpi_iommu_fwspec_init(), so > num_streams==0 could only potentially happen with DT if a fwspec was parsed > using #iommu-cells==0, except arm_smmu_device_dt_probe() would refuse to > probe the entire SMMU if that was anything other than 1, so no, this > definitely cannot ever be out of bounds. Yea, it's unreachable. So, either way is fine. The num_streams guard is already there: doing a dereference after the guard is a common practice anyway. And that drops the Sashiko false positive. Nicolin