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From: Vasant Hegde <vasant.hegde@amd.com>
To: Jean-Christophe Guillain <jean-christophe@guillain.net>, joro@8bytes.org
Cc: suravee.suthikulpanit@amd.com, will@kernel.org,
	robin.murphy@arm.com, iommu@lists.linux.dev,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iommu/amd: Fix NULL pointer dereference for GPUs without upstream bridge
Date: Thu, 5 Nov 2026 09:06:53 +0530	[thread overview]
Message-ID: <1640e445-de18-4ace-b84e-75589ff69727@amd.com> (raw)
In-Reply-To: <20261103151607.435642-1-jean-christophe@guillain.net>



On 11/3/2026 8:46 PM, Jean-Christophe Guillain wrote:
> [You don't often get email from jean-christophe@guillain.net. 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 <jean-christophe@guillain.net>

Thanks Jean! Queued for rc.

-Vasant


      reply	other threads:[~2026-11-05  3:37 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <6a3cf464-6c1b-460a-9ee5-5468ded48e0a@amd.com>
2026-11-03 15:16 ` Jean-Christophe Guillain
2026-11-05  3:36   ` Vasant Hegde [this message]

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