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From: Leon Romanovsky <leon@kernel.org>
To: Alex Mastro <amastro@fb.com>
Cc: "Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christian König" <christian.koenig@amd.com>,
	"Alex Williamson" <alex@shazbot.org>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Kevin Tian" <kevin.tian@intel.com>,
	"Nicolin Chen" <nicolinc@nvidia.com>,
	linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, "Ankit Agrawal" <ankita@nvidia.com>
Subject: Re: [PATCH] dma-buf: fix integer overflow in fill_sg_entry() for buffers >= 8GiB
Date: Wed, 26 Nov 2025 09:18:10 +0200	[thread overview]
Message-ID: <20251126071810.GF12483@unreal> (raw)
In-Reply-To: <20251125-dma-buf-overflow-v1-1-b70ea1e6c4ba@fb.com>

On Tue, Nov 25, 2025 at 05:11:18PM -0800, Alex Mastro wrote:
> fill_sg_entry() splits large DMA buffers into multiple scatter-gather
> entries, each holding up to UINT_MAX bytes. When calculating the DMA
> address for entries beyond the second one, the expression (i * UINT_MAX)
> causes integer overflow due to 32-bit arithmetic.
> 
> This manifests when the input arg length >= 8 GiB results in looping for
> i >= 2.
> 
> Fix by casting i to dma_addr_t before multiplication.
> 
> Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping routine")
> Signed-off-by: Alex Mastro <amastro@fb.com>
> ---
> More color about how I discovered this in [1] for the commit at [2]:
> 
> [1] https://lore.kernel.org/all/aSZHO6otK0Heh+Qj@devgpu015.cco6.facebook.com
> [2] https://lore.kernel.org/all/20251120-dmabuf-vfio-v9-6-d7f71607f371@nvidia.com
> ---
>  drivers/dma-buf/dma-buf-mapping.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Thanks,
Reviewed-by: Leon Romanovsky <leon@kernel.org>

  reply	other threads:[~2025-11-26  7:18 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-26  1:11 [PATCH] dma-buf: fix integer overflow in fill_sg_entry() for buffers >= 8GiB Alex Mastro
2025-11-26  7:18 ` Leon Romanovsky [this message]
2025-11-26 18:01 ` Jason Gunthorpe
2025-11-26 18:55   ` Alex Williamson
2025-11-28 19:44 ` Alex Williamson

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