linux-kernel - Re: [PATCH] ALSA: scarlett2: Fix a potential memory leak in scarlett2_init

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Message-ID: <6014901d-8fe6-9e80-171e-a1017cc9e0f9@wanadoo.fr>
Date:   Sun, 3 Sep 2023 17:08:19 +0200
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     "Geoffrey D. Bennett" <g@...vu>, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH] ALSA: scarlett2: Fix a potential memory leak in
 scarlett2_init_notify()

Le 03/09/2023 à 16:27, Takashi Iwai a écrit :
> On Sun, 03 Sep 2023 14:41:45 +0200,
> Christophe JAILLET wrote:
>>
>> If kmalloc() fails, we should release 'mixer->urb'.
> 
> This is released at the common error path in mixer.c,
> snd_usb_mixer_free(), hence it's not needed.

Agreed, sorry for the noise.

CJ

> 
> And, even if freeing here, you must NULL-clear mixer->urb, too;
> otherwise it'll lead to double-free.
> 
> 
> thanks,
> 
> Takashi
> 
>>
>> Fixes: 9e4d5c1be21f ("ALSA: usb-audio: Scarlett Gen 2 mixer interface")
>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>> ---
>>   sound/usb/mixer_scarlett_gen2.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
>> index 9d11bb08667e..a439c7f64b2e 100644
>> --- a/sound/usb/mixer_scarlett_gen2.c
>> +++ b/sound/usb/mixer_scarlett_gen2.c
>> @@ -4060,8 +4060,10 @@ 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,
>> -- 
>> 2.34.1
>>
>