ALSA: line6: Fix NULL dereference at podhd_disconnect()

When podhd_init() failed with the acquiring a ctrl i/f, the line6
helper still calls the disconnect callback that eventually calls again
usb_driver_release_interface() with the NULL intf.

Put the proper NULL check before calling it for avoiding an Oops.

Fixes: fc90172ba283 ("ALSA: line6: Claim pod x3 usb data interface")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/line6/podhd.c b/sound/usb/line6/podhd.c
index 14ab82e..451007c 100644 (file)
--- a/sound/usb/line6/podhd.c
+++ b/sound/usb/line6/podhd.c
@@ -301,7 +301,8 @@ static void podhd_disconnect(struct usb_line6 *line6)
 
                intf = usb_ifnum_to_if(line6->usbdev,
                                        pod->line6.properties->ctrl_if);
-               usb_driver_release_interface(&podhd_driver, intf);
+               if (intf)
+                       usb_driver_release_interface(&podhd_driver, intf);
        }
 }