From: Jason Gunthorpe <jgg@ziepe.ca>
To: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Cc: Alex Mastro <amastro@fb.com>,
Alex Williamson <alex.williamson@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vfio: fix VFIO_IOMMU_UNMAP_DMA when end of range would overflow u64
Date: Tue, 7 Oct 2025 08:48:08 -0300 [thread overview]
Message-ID: <20251007114808.GB3441843@ziepe.ca> (raw)
In-Reply-To: <68e18f2c-79ad-45ec-99b9-99ff68ba5438@oracle.com>
On Mon, Oct 06, 2025 at 09:23:56PM -0400, Alejandro Jimenez wrote:
> I mentioned this issue on the cover letter for:
> https://lore.kernel.org/qemu-devel/20250919213515.917111-1-alejandro.j.jimenez@oracle.com/
Use iommufd for this kind of work?
> I mentioned in the notes for the patch above why I chose a slightly more
> complex method than the '- 1' approach, since there is a chance that
> iova+size could also go beyond the end of the address space and actually
> wrap around.
At the uapi boundary it should check that size != 0 and
!check_add_overflow(iova+size). It is much easier to understand if the
input from userspace is validated immediately at userspace.
Then the rest of the code safely computes the last with 'iova+size-1'
and does range logic based on last not end.
Jason
next prev parent reply other threads:[~2025-10-07 11:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-06 3:38 [PATCH] vfio: fix VFIO_IOMMU_UNMAP_DMA when end of range would overflow u64 Alex Mastro
2025-10-06 12:16 ` Jason Gunthorpe
2025-10-06 16:29 ` Alex Mastro
2025-10-06 22:50 ` Jason Gunthorpe
2025-10-07 0:39 ` Alex Mastro
2025-10-07 1:23 ` Alejandro Jimenez
2025-10-07 4:24 ` Alex Mastro
2025-10-07 14:41 ` Alejandro Jimenez
2025-10-07 20:43 ` Alex Williamson
2025-10-07 22:57 ` Alex Mastro
2025-10-07 11:48 ` Jason Gunthorpe [this message]
2025-10-07 14:46 ` Alejandro Jimenez
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