linux-kernel - Re: [PATCH] usb: gadget: pch_udc: add checks for dma mapping errors

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Date:   Wed, 23 Aug 2017 18:02:27 -0700
From:   Jack Pham <jackp@...eaurora.org>
To:     Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        ldv-project@...uxtesting.org
Subject: Re: [PATCH] usb: gadget: pch_udc: add checks for dma mapping errors

On Thu, Aug 24, 2017 at 01:47:08AM +0300, Alexey Khoroshilov wrote:
> There are no checks for dma mapping errors in pch_udc.
> Tha patch adds the checks and error handling code.
> Compile tested only.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Alexey Khoroshilov <khoroshilov@...ras.ru>
> ---
>  drivers/usb/gadget/udc/pch_udc.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/pch_udc.c b/drivers/usb/gadget/udc/pch_udc.c
> index 84dcbcd756f0..a305f8392082 100644
> --- a/drivers/usb/gadget/udc/pch_udc.c
> +++ b/drivers/usb/gadget/udc/pch_udc.c
> @@ -1767,7 +1767,7 @@ static struct usb_request *pch_udc_alloc_request(struct usb_ep *usbep,
>  	req->req.dma = DMA_ADDR_INVALID;
>  	req->dma = DMA_ADDR_INVALID;
>  	INIT_LIST_HEAD(&req->queue);
> -	if (!ep->dev->dma_addr)
> +	if (ep->dev->dma_addr != DMA_ADDR_INVALID)
>  		return &req->req;
>  	/* ep0 in requests are allocated from data pool here */
>  	dma_desc = dma_pool_alloc(ep->dev->data_requests, gfp,
> @@ -1879,6 +1879,13 @@ static int pch_udc_pcd_queue(struct usb_ep *usbep, struct usb_request *usbreq,
>  							  usbreq->length,
>  							  DMA_FROM_DEVICE);
>  		}
> +		if (dma_mapping_error(&dev->pdev->dev, req->dma)) {
> +			req->dma = DMA_ADDR_INVALID;
> +			retval = -ENOMEM;
> +			if ((unsigned long)(usbreq->buf) & 0x03)
> +				kfree(req->buf);
> +			goto probe_end;
> +		}
>  		req->dma_mapped = 1;
>  	}
>  	if (usbreq->length > 0) {
> @@ -2961,6 +2968,10 @@ static int init_dma_pools(struct pch_udc_dev *dev)
>  	dev->dma_addr = dma_map_single(&dev->pdev->dev, ep0out_buf,
>  				       UDC_EP0OUT_BUFF_SIZE * 4,
>  				       DMA_FROM_DEVICE);
> +	if (dma_mapping_error(&dev->pdev->dev, dev->dma_addr)) {
> +		dev->dma_addr = DMA_ADDR_INVALID;
> +		return -ENOMEM;
> +	}

Wouldn't this driver be better off using the
usb_gadget_{map,unmap}_request() functions provided by UDC core.c?
dma_mapping_error() is provided for free that way.

Jack
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