linux-kernel - Re: [PATCH v11 09/12] vduse: take out allocations from vduse_dev_alloc

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Message-ID: <20260110185006-mutt-send-email-mst@kernel.org>
Date: Sat, 10 Jan 2026 18:54:03 -0500
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Eugenio Pérez <eperezma@...hat.com>
Cc: linux-kernel@...r.kernel.org, virtualization@...ts.linux.dev,
	Maxime Coquelin <mcoqueli@...hat.com>,
	Laurent Vivier <lvivier@...hat.com>, Cindy Lu <lulu@...hat.com>,
	jasowang@...hat.com, Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Stefano Garzarella <sgarzare@...hat.com>,
	Yongji Xie <xieyongji@...edance.com>
Subject: Re: [PATCH v11 09/12] vduse: take out allocations from
 vduse_dev_alloc_coherent

On Fri, Jan 09, 2026 at 04:24:27PM +0100, Eugenio Pérez wrote:
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 82ee476d45e0..675da1465e0e 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -923,16 +923,24 @@ static void *vduse_dev_alloc_coherent(union virtio_map token, size_t size,
>  	if (!token.group)
>  		return NULL;
>  
> +	addr = alloc_pages_exact(size, flag);
> +	if (!addr)
> +		return NULL;
> +

So addr has allocated pages here ...


>  	vdev = token.group->dev;
>  	domain = vdev->domain;
>  	addr = vduse_domain_alloc_coherent(domain, size,
> -					   (dma_addr_t *)&iova, flag);
> +					   (dma_addr_t *)&iova, addr);

and then is overwritten here ...

>  	if (!addr)
> -		return NULL;
> +		goto err;

except on error where we go to err ...

>  
>  	*dma_addr = (dma_addr_t)iova;
>  
>  	return addr;
> +
> +err:
> +	free_pages_exact(addr, size);

only to try and free NULL. will leak the original pages, will it not.

> +	return NULL;
>  }
>  
>  static void vduse_dev_free_coherent(union virtio_map token, size_t size,