Hello,
On Saturday, May 18, 2019 7:49:49 PM CEST you wrote:
> On Sat, 18 May 2019, syzbot wrote:
> >
> > syzbot has tested the proposed patch but the reproducer still triggered
> > crash:
> > KASAN: use-after-free Read in usb_driver_release_interface
> >
> > usb 1-1: Loading firmware file isl3887usb
> > usb 1-1: Direct firmware load for isl3887usb failed with error -2
> > usb 1-1: Firmware not found.
> > p54usb 1-1:0.143: failed to initialize device (-2)
> > ==================================================================
> > BUG: KASAN: use-after-free in usb_driver_release_interface+0x16b/0x190
> > drivers/usb/core/driver.c:584
> > Read of size 8 at addr ffff88808fc31218 by task kworker/0:1/12
>
> Now the bad access is in a different place. That's a good sign.
> In this case it indicates that although udev is still hanging around,
> intf has already been freed. We really should acquire a reference to
> it instead.
>
> Alan Stern
Thanks. I can confirm that it works with the real ISL3887
hardware as well. Can you please spin up a patch or how
should this be continued?
Cheers,
Christian
> drivers/net/wireless/intersil/p54/p54usb.c | 43 ++++++++++++-----------------
> 1 file changed, 18 insertions(+), 25 deletions(-)
>
> Index: usb-devel/drivers/net/wireless/intersil/p54/p54usb.c
> ===================================================================
> --- usb-devel.orig/drivers/net/wireless/intersil/p54/p54usb.c
> +++ usb-devel/drivers/net/wireless/intersil/p54/p54usb.c
> @@ -33,6 +33,8 @@ MODULE_ALIAS("prism54usb");
> MODULE_FIRMWARE("isl3886usb");
> MODULE_FIRMWARE("isl3887usb");
>
> +static struct usb_driver p54u_driver;
> +
> /*
> * Note:
> *
> @@ -921,9 +923,9 @@ static void p54u_load_firmware_cb(const
> {
> struct p54u_priv *priv = context;
> struct usb_device *udev = priv->udev;
> + struct usb_interface *intf = priv->intf;
> int err;
>
> - complete(&priv->fw_wait_load);
> if (firmware) {
> priv->fw = firmware;
> err = p54u_start_ops(priv);
> @@ -932,26 +934,22 @@ static void p54u_load_firmware_cb(const
> dev_err(&udev->dev, "Firmware not found.\n");
> }
>
> - if (err) {
> - struct device *parent = priv->udev->dev.parent;
> -
> - dev_err(&udev->dev, "failed to initialize device (%d)\n", err);
> -
> - if (parent)
> - device_lock(parent);
> + complete(&priv->fw_wait_load);
> + /*
> + * At this point p54u_disconnect may have already freed
> + * the "priv" context. Do not use it anymore!
> + */
> + priv = NULL;
>
> - device_release_driver(&udev->dev);
> - /*
> - * At this point p54u_disconnect has already freed
> - * the "priv" context. Do not use it anymore!
> - */
> - priv = NULL;
> + if (err) {
> + dev_err(&intf->dev, "failed to initialize device (%d)\n", err);
>
> - if (parent)
> - device_unlock(parent);
> + usb_lock_device(udev);
> + usb_driver_release_interface(&p54u_driver, intf);
> + usb_unlock_device(udev);
> }
>
> - usb_put_dev(udev);
> + usb_put_intf(intf);
> }
>
> static int p54u_load_firmware(struct ieee80211_hw *dev,
> @@ -972,14 +970,14 @@ static int p54u_load_firmware(struct iee
> dev_info(&priv->udev->dev, "Loading firmware file %s\n",
> p54u_fwlist[i].fw);
>
> - usb_get_dev(udev);
> + usb_get_intf(intf);
> err = request_firmware_nowait(THIS_MODULE, 1, p54u_fwlist[i].fw,
> device, GFP_KERNEL, priv,
> p54u_load_firmware_cb);
> if (err) {
> dev_err(&priv->udev->dev, "(p54usb) cannot load firmware %s "
> "(%d)!\n", p54u_fwlist[i].fw, err);
> - usb_put_dev(udev);
> + usb_put_intf(intf);
> }
>
> return err;
> @@ -1011,8 +1009,6 @@ static int p54u_probe(struct usb_interfa
> skb_queue_head_init(&priv->rx_queue);
> init_usb_anchor(&priv->submitted);
>
> - usb_get_dev(udev);
> -
> /* really lazy and simple way of figuring out if we're a 3887 */
> /* TODO: should just stick the identification in the device table */
> i = intf->altsetting->desc.bNumEndpoints;
> @@ -1053,10 +1049,8 @@ static int p54u_probe(struct usb_interfa
> priv->upload_fw = p54u_upload_firmware_net2280;
> }
> err = p54u_load_firmware(dev, intf);
> - if (err) {
> - usb_put_dev(udev);
> + if (err)
> p54_free_common(dev);
> - }
> return err;
> }
>
> @@ -1072,7 +1066,6 @@ static void p54u_disconnect(struct usb_i
> wait_for_completion(&priv->fw_wait_load);
> p54_unregister_common(dev);
>
> - usb_put_dev(interface_to_usbdev(intf));
> release_firmware(priv->fw);
> p54_free_common(dev);
> }
>
>
