linux-kernel - Re: [PATCH] media: videobuf2: Fix device reference leak in vb2_dc

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Message-ID: <aaac0d2b-ec3f-4469-9334-a7216b85b33f@samsung.com>
Date: Tue, 28 Oct 2025 08:10:01 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Haotian Zhang <vulab@...as.ac.cn>, tfiga@...omium.org, Mauro Carvalho
	Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: videobuf2: Fix device reference leak in
 vb2_dc_alloc error path

On 28.10.2025 07:44, Haotian Zhang wrote:
> In vb2_dc_alloc(), get_device() is called to increment the device
> reference count. However, if subsequent DMA allocation fails
> (vb2_dc_alloc_coherent or vb2_dc_alloc_non_coherent returns error),
> the function returns without calling put_device(), causing a device
> reference leak.
>
> Add put_device() call in the error path before kfree() to properly
> release the device reference acquired earlier.
>
> Fixes: de27891f675e ("media: videobuf2: handle non-contiguous DMA allocations")
> Signed-off-by: Haotian Zhang <vulab@...as.ac.cn>
Reviewed-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>   drivers/media/common/videobuf2/videobuf2-dma-contig.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index a13ec569c82f..7123c5fae92c 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -258,6 +258,7 @@ static void *vb2_dc_alloc(struct vb2_buffer *vb,
>   
>   	if (ret) {
>   		dev_err(dev, "dma alloc of size %lu failed\n", size);
> +		put_device(buf->dev);
>   		kfree(buf);
>   		return ERR_PTR(-ENOMEM);
>   	}

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland