Re: [PATCH] rtl818x: fix potential use after free

[Larry Finger]

On 11/29/18 4:48 AM, Pan Bian wrote:
> entry is released via usb_put_urb just after calling usb_submit_urb.
> However, entry is used if the submission fails, resulting in a use after
> free bug. The patch fixes this.
>
> Signed-off-by: Pan Bian <bianpan2016@xxxxxxx>
> ---
>   drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> index cec3778..1a2ea8b 100644
> --- a/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> +++ b/drivers/net/wireless/realtek/rtl818x/rtl8187/dev.c
> @@ -444,12 +444,13 @@ static int rtl8187_init_urbs(struct ieee80211_hw *dev)
>   		skb_queue_tail(&priv->rx_queue, skb);
>   		usb_anchor_urb(entry, &priv->anchored);
>   		ret = usb_submit_urb(entry, GFP_KERNEL);
> -		usb_put_urb(entry);
>   		if (ret) {
>   			skb_unlink(skb, &priv->rx_queue);
>   			usb_unanchor_urb(entry);
> +			usb_put_urb(entry);
>   			goto err;
>   		}
> +		usb_put_urb(entry);
>   	}
>   	return ret;

Good catch.

ACKed-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>

Thanks,
Larry