linux-kernel - Re: [PATCH] ALSA: scarlett2: Prevent leaking urb

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Date: Tue, 21 May 2024 15:02:18 +0200
From: Takashi Iwai <tiwai@...e.de>
To: Chen Ni <nichen@...as.ac.cn>
Cc: g@...vu,
	perex@...ex.cz,
	tiwai@...e.com,
	alsa-devel@...a-project.org,
	linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: scarlett2: Prevent leaking urb

On Tue, 21 May 2024 03:03:52 +0200,
Chen Ni wrote:
> 
> In scarlett2_init_notify() if kmalloc() fails the allocated urb should
> be released.

It's freed in the common USB mixer destructor (snd_usb_mixer_free()),
hence your patch will lead to a double-free.


thanks,

Takashi

> 
> Signed-off-by: Chen Ni <nichen@...as.ac.cn>
> ---
>  sound/usb/mixer_scarlett2.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
> index 1150cf104985..4cad6b2a0292 100644
> --- a/sound/usb/mixer_scarlett2.c
> +++ b/sound/usb/mixer_scarlett2.c
> @@ -8637,9 +8637,10 @@ static int scarlett2_init_notify(struct usb_mixer_interface *mixer)
>  		return -ENOMEM;
>  
>  	transfer_buffer = kmalloc(private->wMaxPacketSize, GFP_KERNEL);
> -	if (!transfer_buffer)
> +	if (!transfer_buffer) {
> +		usb_free_urb(mixer->urb);
>  		return -ENOMEM;
> -
> +	}
>  	usb_fill_int_urb(mixer->urb, dev, pipe,
>  			 transfer_buffer, private->wMaxPacketSize,
>  			 scarlett2_notify, mixer, private->bInterval);
> -- 
> 2.25.1
> 
>