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Received: from BL4PR12MB9505.namprd12.prod.outlook.com (2603:10b6:208:591::16) by SA1PR12MB8644.namprd12.prod.outlook.com (2603:10b6:806:384::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.592.10; Thu, 5 Nov 2026 03:36:59 +0000 Received: from BL4PR12MB9505.namprd12.prod.outlook.com ([fe80::73aa:eb8c:a86b:5a83]) by BL4PR12MB9505.namprd12.prod.outlook.com ([fe80::73aa:eb8c:a86b:5a83%5]) with mapi id 15.21.0592.009; Thu, 5 Nov 2026 03:36:59 +0000 Message-ID: <1640e445-de18-4ace-b84e-75589ff69727@amd.com> Date: Thu, 5 Nov 2026 09:06:53 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] iommu/amd: Fix NULL pointer dereference for GPUs without upstream bridge To: Jean-Christophe Guillain , joro@8bytes.org Cc: suravee.suthikulpanit@amd.com, will@kernel.org, robin.murphy@arm.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: <6a3cf464-6c1b-460a-9ee5-5468ded48e0a@amd.com> <20261103151607.435642-1-jean-christophe@guillain.net> Content-Language: en-US From: Vasant Hegde In-Reply-To: <20261103151607.435642-1-jean-christophe@guillain.net> Content-Type: text/plain; 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Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] > > pci_upstream_bridge() can return NULL for devices without an upstream > bridge. The AMD GPU identity mapping quirk dereferences the returned > pointer unconditionally, causing a kernel panic during boot. > > Check the pointer before accessing the bridge vendor ID. > > This fixes a boot regression on a Lenovo system with an AMD PRO > A10-9700E APU. The system now boots with AMD IOMMU enabled. > > Fixes: bf5bdfd1f8d4 ("iommu/amd: Force identity mode for selected GPUs only") > > Signed-off-by: Jean-Christophe Guillain Thanks Jean! Queued for rc. -Vasant