Re: [PATCH 1/2] usb: hso: fix error handling code of hso_create_net_device

[Dongliang Mu]

On Wed, Jul 14, 2021 at 3:16 PM Dongliang Mu <mudongliangabcd@xxxxxxxxx> wrote:
>
> The current error handling code of hso_create_net_device is
> hso_free_net_device, no matter which errors lead to. For example,
> WARNING in hso_free_net_device [1].

Although there is already a patch for the above bug report, I don't
think it cannot handle all kinds of errors caused in
hso_create_net_device.

So refactoring the error handling code is the only way to fix this issue.

[1] https://syzkaller.appspot.com/text?tag=Patch&x=1188fcc6600000

>
> Fix this by refactoring the error handling code of
> hso_create_net_device by handling different errors by different code.
>
> [1] https://syzkaller.appspot.com/bug?id=66eff8d49af1b28370ad342787413e35bbe76efe
>
> Reported-by: syzbot+44d53c7255bb1aea22d2@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 5fcfb6d0bfcd ("hso: fix bailout in error case of probe")
> Signed-off-by: Dongliang Mu <mudongliangabcd@xxxxxxxxx>
> ---
>  drivers/net/usb/hso.c | 37 +++++++++++++++++++++++++++----------
>  1 file changed, 27 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
> index 54ef8492ca01..90fa4d9fa119 100644
> --- a/drivers/net/usb/hso.c
> +++ b/drivers/net/usb/hso.c
> @@ -2495,7 +2495,9 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
>                            hso_net_init);
>         if (!net) {
>                 dev_err(&interface->dev, "Unable to create ethernet device\n");
> -               goto exit;
> +               kfree(hso_dev);
> +       usb_free_urb(hso_net->mux_bulk_tx_urb);
> +               return NULL;
>         }
>
>         hso_net = netdev_priv(net);
> @@ -2508,13 +2510,13 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
>                                       USB_DIR_IN);
>         if (!hso_net->in_endp) {
>                 dev_err(&interface->dev, "Can't find BULK IN endpoint\n");
> -               goto exit;
> +               goto err_get_ep;
>         }
>         hso_net->out_endp = hso_get_ep(interface, USB_ENDPOINT_XFER_BULK,
>                                        USB_DIR_OUT);
>         if (!hso_net->out_endp) {
>                 dev_err(&interface->dev, "Can't find BULK OUT endpoint\n");
> -               goto exit;
> +               goto err_get_ep;
>         }
>         SET_NETDEV_DEV(net, &interface->dev);
>         SET_NETDEV_DEVTYPE(net, &hso_type);
> @@ -2523,18 +2525,18 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
>         for (i = 0; i < MUX_BULK_RX_BUF_COUNT; i++) {
>                 hso_net->mux_bulk_rx_urb_pool[i] = usb_alloc_urb(0, GFP_KERNEL);
>                 if (!hso_net->mux_bulk_rx_urb_pool[i])
> -                       goto exit;
> +                       goto err_mux_bulk_rx;
>                 hso_net->mux_bulk_rx_buf_pool[i] = kzalloc(MUX_BULK_RX_BUF_SIZE,
>                                                            GFP_KERNEL);
>                 if (!hso_net->mux_bulk_rx_buf_pool[i])
> -                       goto exit;
> +                       goto err_mux_bulk_rx;
>         }
>         hso_net->mux_bulk_tx_urb = usb_alloc_urb(0, GFP_KERNEL);
>         if (!hso_net->mux_bulk_tx_urb)
> -               goto exit;
> +               goto err_mux_bulk_tx;
>         hso_net->mux_bulk_tx_buf = kzalloc(MUX_BULK_TX_BUF_SIZE, GFP_KERNEL);
>         if (!hso_net->mux_bulk_tx_buf)
> -               goto exit;
> +               goto err_mux_bulk_tx;
>
>         add_net_device(hso_dev);
>
> @@ -2542,7 +2544,7 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
>         result = register_netdev(net);
>         if (result) {
>                 dev_err(&interface->dev, "Failed to register device\n");
> -               goto exit;
> +               goto err_register;
>         }
>
>         hso_log_port(hso_dev);
> @@ -2550,8 +2552,23 @@ static struct hso_device *hso_create_net_device(struct usb_interface *interface,
>         hso_create_rfkill(hso_dev, interface);
>
>         return hso_dev;
> -exit:
> -       hso_free_net_device(hso_dev, true);
> +
> +err_register:
> +       unregister_netdev(net);
> +       remove_net_device(hso_dev);
> +err_mux_bulk_tx:
> +       kfree(hso_net->mux_bulk_tx_buf);
> +       hso_net->mux_bulk_tx_buf = NULL;
> +       usb_free_urb(hso_net->mux_bulk_tx_urb);
> +err_mux_bulk_rx:
> +       for (i = 0; i < MUX_BULK_RX_BUF_COUNT; i++) {
> +               usb_free_urb(hso_net->mux_bulk_rx_urb_pool[i]);
> +               kfree(hso_net->mux_bulk_rx_buf_pool[i]);
> +               hso_net->mux_bulk_rx_buf_pool[i] = NULL;
> +       }
> +err_get_ep:
> +       free_netdev(net);
> +       kfree(hso_dev);
>         return NULL;
>  }
>
> --
> 2.25.1
>