From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 9 Oct 2017 12:26:27 +0000 (+0200)
Subject: ALSA: line6: Fix NULL dereference at podhd_disconnect()
X-Git-Tag: Ubuntu-4.13.0-17.20~42
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=f2ad09b00bc646efde987eb13b486502d9feffaa;p=mirror_ubuntu-artful-kernel.git

ALSA: line6: Fix NULL dereference at podhd_disconnect()

BugLink: http://bugs.launchpad.net/bugs/1724669

commit 54a4b2b45817ea2365b40c923c098a26af0c0dbb upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
---

diff --git a/sound/usb/line6/podhd.c b/sound/usb/line6/podhd.c
index 956f847a96e4..cfcd80092a54 100644
--- 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);
 	}
 }