Re: [PATCH] usb: renesas_usbhs: fix NULL pointer dereference in dma_release_channel()

[Simon Horman <horms@verge.net.au>]

On Fri, Jan 30, 2015 at 03:58:23PM +0900, Yoshihiro Shimoda wrote:
> This patch fixes an issue that the following commit causes NULL
> pointer dereference in dma_release_channel().
>  "usb: renesas_usbhs: add support for requesting DT DMA"
>  (commit id abd2dbf6bb1b5f3a03a8c76b1a8879da1dd30caa)
> 
> The usbhsf_dma_init_dt() should set fifo->{t,r}x_chan to NULL if
> dma_request_slave_channel_reason() returns IS_ERR value.
> Otherwise, usbhsf_dma_quit() will call dma_release_channel(), and then
> NULL pointer dereference happens.
> 
> Reported-by: Simon Horman <horms@verge.net.au>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

I have tested this on the lager and koelsch boards using
shmobile_defconfig and next-20150129 as a base. The environment
where I originally observed the problem.

Tested-by: Simon Horman <horms+renesas@verge.net.au>

> ---
> This patch is based on Felipe's usb.git / testing/next branch.
> (commit id }b3990cb707ff91cd6507d53a0a730afe97)
> 
>  drivers/usb/renesas_usbhs/fifo.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
> index 4c086b1..d891bff 100644
> --- a/drivers/usb/renesas_usbhs/fifo.c
> +++ b/drivers/usb/renesas_usbhs/fifo.c
> @@ -1072,7 +1072,11 @@ static void usbhsf_dma_init_pdev(struct usbhs_fifo *fifo)
>  static void usbhsf_dma_init_dt(struct device *dev, struct usbhs_fifo *fifo)
>  {
>  	fifo->tx_chan = dma_request_slave_channel_reason(dev, "tx");
> +	if (IS_ERR(fifo->tx_chan))
> +		fifo->tx_chan = NULL;
>  	fifo->rx_chan = dma_request_slave_channel_reason(dev, "rx");
> +	if (IS_ERR(fifo->rx_chan))
> +		fifo->rx_chan = NULL;
>  }
>  
>  static void usbhsf_dma_init(struct usbhs_priv *priv,
> -- 
> 1.7.9.5
>