Re: [PATCH] ALSA: usb-audio: Fix a potential memory leak in scarlett2_init_notify()

Christophe JAILLET
2023-09-03T19:43:05Z

Le 03/09/2023 à 18:37, Takashi Iwai a écrit :
> On Sun, 03 Sep 2023 17:04:47 +0200,
...

> Indeed. The fix would be rather a oneliner like below, though:

Looks much better than mine :)

I let you send the patch, it is your solution.

Just for my understanding, how is snd_ump_ops used, especially .open?
I've not been able to figure out where it was called.

In alloc_midi_urbs(), if usb_alloc_coherent() fails, then
ctx->urb->transfer_buffer could be anything because usb_fill_xxx_urb()
is not called.
So there could be an edge case where your fix could still be incomplete.

For the start_input_streams() caller, this is fine, because the
corresponding memory is kzalloc()'ed in start_input_streams() at some
point, but I've not been able to check for snd_usb_midi_v2_open().

CJ

>
> --- a/sound/usb/midi2.c
> +++ b/sound/usb/midi2.c
> @@ -265,7 +265,7 @@ static void free_midi_urbs(struct snd_usb_midi2_endpoint *ep)
>
> if (!ep)
> return;
> - for (i = 0; i < ep->num_urbs; ++i) {
> + for (i = 0; i < NUM_URBS; ++i) {
> ctx = &ep->urbs[i];
> if (!ctx->urb)
> break;
>
> That was the intended behavior of free_midi_urbs().
>
>
> Takashi
>