linux-kernel - Re: [PATCH] sound: usb: line6: free allocated urbs on failure

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Message-ID: <s5hy2a8xeb7.wl-tiwai@suse.de>
Date:   Thu, 15 Jul 2021 08:48:44 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Salah Triki <salah.triki@...il.com>
Cc:     perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sound: usb: line6: free allocated urbs on failure

On Thu, 15 Jul 2021 02:56:25 +0200,
Salah Triki wrote:
> 
> Free allocated urbs on failure in order to prevent memory leaks.
> 
> Signed-off-by: Salah Triki <salah.triki@...il.com>

This will lead to double-free.  The resources are freed in the
destructor of PCM component, line6_cleanup_pcm().


Takashi


> ---
>  sound/usb/line6/capture.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/sound/usb/line6/capture.c b/sound/usb/line6/capture.c
> index 970c9bdce0b2..345b75ede5d5 100644
> --- a/sound/usb/line6/capture.c
> +++ b/sound/usb/line6/capture.c
> @@ -258,6 +258,7 @@ int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm)
>  {
>  	struct usb_line6 *line6 = line6pcm->line6;
>  	int i;
> +	int ret;
>  
>  	line6pcm->in.urbs = kcalloc(line6->iso_buffers, sizeof(struct urb *),
>  				    GFP_KERNEL);
> @@ -272,8 +273,10 @@ int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm)
>  		urb = line6pcm->in.urbs[i] =
>  		    usb_alloc_urb(LINE6_ISO_PACKETS, GFP_KERNEL);
>  
> -		if (urb == NULL)
> -			return -ENOMEM;
> +		if (urb == NULL) {
> +			ret = -ENOMEM;
> +			goto enomem;
> +		}
>  
>  		urb->dev = line6->usbdev;
>  		urb->pipe =
> @@ -286,9 +289,20 @@ int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm)
>  		urb->interval = LINE6_ISO_INTERVAL;
>  		urb->error_count = 0;
>  		urb->complete = audio_in_callback;
> -		if (usb_urb_ep_type_check(urb))
> -			return -EINVAL;
> +		if (usb_urb_ep_type_check(urb)) {
> +			ret = -EINVAL;
> +			goto einval;
> +		}
>  	}
>  
>  	return 0;
> +
> +enomem:
> +	i--;
> +
> +einval:
> +	while (i >= 0)
> +		usb_free_urb(line6pcm->in.urbs[i--]);
> +
> +	return ret;
>  }
> -- 
> 2.25.1
>