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

Takashi Iwai
2023-09-03T14:24:03Z

On Sun, 03 Sep 2023 15:06:00 +0200,
Christophe JAILLET wrote:
>
> If usb_alloc_coherent() or usb_urb_ep_type_check() fail, we should release
> the resources previously allocated.

Those are freed in the caller side, start_input_streams() instead.

thanks,

Takashi

>
> Fixes: ff49d1df79ae ("ALSA: usb-audio: USB MIDI 2.0 UMP support")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> sound/usb/midi2.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/sound/usb/midi2.c b/sound/usb/midi2.c
> index a27e244650c8..4109c82adff6 100644
> --- a/sound/usb/midi2.c
> +++ b/sound/usb/midi2.c
> @@ -302,7 +302,8 @@ static int alloc_midi_urbs(struct snd_usb_midi2_endpoint *ep)
> ctx->urb = usb_alloc_urb(0, GFP_KERNEL);
> if (!ctx->urb) {
> dev_err(&ep->dev->dev, "URB alloc failed\n");
> - return -ENOMEM;
> + err = -ENOMEM;
> + goto err_free_all;
> }
> ctx->ep = ep;
> buffer = usb_alloc_coherent(ep->dev, len, GFP_KERNEL,
> @@ -310,7 +311,8 @@ static int alloc_midi_urbs(struct snd_usb_midi2_endpoint *ep)
> if (!buffer) {
> dev_err(&ep->dev->dev,
> "URB buffer alloc failed (size %d)\n", len);
> - return -ENOMEM;
> + err = -ENOMEM;
> + goto err_free_cur_urb;
> }
> if (ep->interval)
> usb_fill_int_urb(ctx->urb, ep->dev, ep->pipe,
> @@ -322,13 +324,22 @@ static int alloc_midi_urbs(struct snd_usb_midi2_endpoint *ep)
> if (err < 0) {
> dev_err(&ep->dev->dev, "invalid MIDI EP %x\n",
> endpoint);
> - return err;
> + goto err_free_cur_dma;
> }
> ctx->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
> ep->num_urbs++;
> }
> ep->urb_free = ep->urb_free_mask = GENMASK(ep->num_urbs - 1, 0);
> return 0;
> +
> +err_free_cur_dma:
> + usb_free_coherent(ep->dev, len, buffer, ctx->urb->transfer_dma);
> +err_free_cur_urb:
> + usb_free_urb(ctx->urb);
> + ctx->urb = NULL;
> +err_free_all:
> + free_midi_urbs(ep);
> + return err;
> }
>
> static struct snd_usb_midi2_endpoint *
> --
> 2.34.1
>