linux-kernel - Re: [PATCH] ALSA: usb-audio: Fix memory leak in __snd_usbmidi

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Message-ID: <s5hpnihmlk3.wl-tiwai@suse.de>
Date:   Mon, 28 Oct 2019 07:27:40 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Navid Emamdoost <navid.emamdoost@...il.com>
Cc:     emamd001@....edu, kjlu@....edu, smccaman@....edu,
        Clemens Ladisch <clemens@...isch.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: usb-audio: Fix memory leak in __snd_usbmidi_create

On Sun, 27 Oct 2019 23:10:06 +0100,
Navid Emamdoost wrote:
> 
> In the implementation of __snd_usbmidi_create() there is a memory leak
> caused by incorrect goto destination. Go to free_midi if
> snd_usbmidi_create_endpoints_midiman() or snd_usbmidi_create_endpoints()
> fail.

No, this will lead to double-free.  After registering the rawmidi
interface at snd_usbmidi_create_rawmidi(), the common destructor will
be called via rawmidi private_free callback, and this will release the
all resources already.


thanks,

Takashi

> 
> Fixes: 731209cc0417 ("ALSA: usb-midi: Use common error handling code in __snd_usbmidi_create()")
> Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
> ---
>  sound/usb/midi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/usb/midi.c b/sound/usb/midi.c
> index b737f0ec77d0..22db37fbfbbd 100644
> --- a/sound/usb/midi.c
> +++ b/sound/usb/midi.c
> @@ -2476,7 +2476,7 @@ int __snd_usbmidi_create(struct snd_card *card,
>  	else
>  		err = snd_usbmidi_create_endpoints(umidi, endpoints);
>  	if (err < 0)
> -		goto exit;
> +		goto free_midi;
>  
>  	usb_autopm_get_interface_no_resume(umidi->iface);
>  
> -- 
> 2.17.1
>