ALSA: scarlett2: Fix a potential memory leak in scarlett2_init_notify()

[PATCH] ALSA: scarlett2: Fix a potential memory leak in scarlett2_init_notify()

Posted by Christophe JAILLET 2 years, 3 months ago

If kmalloc() fails, we should release 'mixer->urb'.

Fixes: 9e4d5c1be21f ("ALSA: usb-audio: Scarlett Gen 2 mixer interface")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.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

Re: [PATCH] ALSA: scarlett2: Fix a potential memory leak in scarlett2_init_notify()

Posted by Takashi Iwai 2 years, 3 months ago

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.

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@wanadoo.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
>

Re: [PATCH] ALSA: scarlett2: Fix a potential memory leak in scarlett2_init_notify()

Posted by Christophe JAILLET 2 years, 3 months ago

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@wanadoo.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
>>
>