linux-kernel - Re: [PATCH][V2] mt7601u: do not free dma

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Date:	Fri, 26 Feb 2016 10:14:59 +1100
From:	Julian Calaby <julian.calaby@...il.com>
To:	Colin King <colin.king@...onical.com>
Cc:	Jakub Kicinski <kubakici@...pl>, Kalle Valo <kvalo@...eaurora.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>,
	"Mailing List, Arm" <linux-arm-kernel@...ts.infradead.org>,
	linux-mediatek@...ts.infradead.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH][V2] mt7601u: do not free dma_buf when ivp allocation fails

Hi Colin,

On Fri, Feb 26, 2016 at 10:09 AM, Colin King <colin.king@...onical.com> wrote:
> From: Colin Ian King <colin.king@...onical.com>
>
> If the allocation of ivp fails the error handling attempts to
> free an uninitialized dma_buf; this data structure just contains
> garbage on the stack, so the freeing will cause issues when the
> urb, buf and dma fields are free'd. Fix this by not free'ing the
> dma_buf if the ivp allocation fails.
>
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/net/wireless/mediatek/mt7601u/mcu.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/wireless/mediatek/mt7601u/mcu.c b/drivers/net/wireless/mediatek/mt7601u/mcu.c
> index fbb1986..70e4b5e 100644
> --- a/drivers/net/wireless/mediatek/mt7601u/mcu.c
> +++ b/drivers/net/wireless/mediatek/mt7601u/mcu.c
> @@ -362,10 +362,10 @@ mt7601u_upload_firmware(struct mt7601u_dev *dev, const struct mt76_fw *fw)
>         int i, ret;
>
>         ivb = kmemdup(fw->ivb, sizeof(fw->ivb), GFP_KERNEL);
> -       if (!ivb || mt7601u_usb_alloc_buf(dev, MCU_FW_URB_SIZE, &dma_buf)) {
> -               ret = -ENOMEM;
> +       if (!ivb)
> +               return -ENOMEM;
> +       if (mt7601u_usb_alloc_buf(dev, MCU_FW_URB_SIZE, &dma_buf))
>                 goto error;

Are you sure this is right? Isn't ret unset here and consequently
returned at the end of the error label?

Thanks,

-- 
Julian Calaby

Email: julian.calaby@...il.com
Profile: http://www.google.com/profiles/julian.calaby/