linux-kernel - Re: [PATCH v4 8/8] vfio: Validate dma-buf revocation semantics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ca33c9d2-3117-4a99-b8f1-e8e2f732fd2a@amd.com>
Date: Wed, 21 Jan 2026 15:18:13 +0100
From: Christian König <christian.koenig@....com>
To: Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>
Cc: Sumit Semwal <sumit.semwal@...aro.org>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Gerd Hoffmann <kraxel@...hat.com>,
 Dmitry Osipenko <dmitry.osipenko@...labora.com>,
 Gurchetan Singh <gurchetansingh@...omium.org>, Chia-I Wu
 <olvaffe@...il.com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Lucas De Marchi <lucas.demarchi@...el.com>,
 Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
 Rodrigo Vivi <rodrigo.vivi@...el.com>, Kevin Tian <kevin.tian@...el.com>,
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Felix Kuehling
 <Felix.Kuehling@....com>, Alex Williamson <alex@...zbot.org>,
 Ankit Agrawal <ankita@...dia.com>,
 Vivek Kasireddy <vivek.kasireddy@...el.com>, linux-media@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
 linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org,
 virtualization@...ts.linux.dev, intel-xe@...ts.freedesktop.org,
 linux-rdma@...r.kernel.org, iommu@...ts.linux.dev, kvm@...r.kernel.org
Subject: Re: [PATCH v4 8/8] vfio: Validate dma-buf revocation semantics

On 1/21/26 14:47, Jason Gunthorpe wrote:
> On Wed, Jan 21, 2026 at 02:59:16PM +0200, Leon Romanovsky wrote:
>> From: Leon Romanovsky <leonro@...dia.com>
>>
>> Use the new dma_buf_attach_revocable() helper to restrict attachments to
>> importers that support mapping invalidation.
>>
>> Signed-off-by: Leon Romanovsky <leonro@...dia.com>
>> ---
>>  drivers/vfio/pci/vfio_pci_dmabuf.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c
>> index 5fceefc40e27..85056a5a3faf 100644
>> --- a/drivers/vfio/pci/vfio_pci_dmabuf.c
>> +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c
>> @@ -31,6 +31,9 @@ static int vfio_pci_dma_buf_attach(struct dma_buf *dmabuf,
>>  	if (priv->revoked)
>>  		return -ENODEV;
>>  
>> +	if (!dma_buf_attach_revocable(attachment))
>> +		return -EOPNOTSUPP;
>> +
>>  	return 0;
>>  }
> 
> We need to push an urgent -rc fix to implement a pin function here
> that always fails. That was missed and it means things like rdma can
> import vfio when the intention was to block that. It would be bad for
> that uAPI mistake to reach a released kernel.
> 
> It's tricky that NULL pin ops means "I support pin" :|

Well it means: "I have no memory management and my buffers are always pinned.".

Christian.

> 
> Jason