linux-kernel - [PATCH 4.9 22/39] ALSA: line6: Fix missing initialization before error path

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Date:   Mon, 16 Oct 2017 18:16:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Konovalov <andreyknvl@...gle.com>,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.9 22/39] ALSA: line6: Fix missing initialization before error path

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Takashi Iwai <tiwai@...e.de>

commit cb02ffc76a53b5ea751b79b8d4f4d180e5868475 upstream.

The error path in podhd_init() tries to clear the pending timer, while
the timer object is initialized at the end of init sequence, thus it
may hit the uninitialized object, as spotted by syzkaller:

  INFO: trying to register non-static key.
  the code is fine but needs lockdep annotation.
  turning off the locking correctness validator.
  CPU: 1 PID: 1845 Comm: kworker/1:2 Not tainted
  4.14.0-rc2-42613-g1488251d1a98 #238
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Workqueue: usb_hub_wq hub_event
  Call Trace:
   __dump_stack lib/dump_stack.c:16
   dump_stack+0x292/0x395 lib/dump_stack.c:52
   register_lock_class+0x6c4/0x1a00 kernel/locking/lockdep.c:769
   __lock_acquire+0x27e/0x4550 kernel/locking/lockdep.c:3385
   lock_acquire+0x259/0x620 kernel/locking/lockdep.c:4002
   del_timer_sync+0x12c/0x280 kernel/time/timer.c:1237
   podhd_disconnect+0x8c/0x160 sound/usb/line6/podhd.c:299
   line6_probe+0x844/0x1310 sound/usb/line6/driver.c:783
   podhd_probe+0x64/0x70 sound/usb/line6/podhd.c:474
   ....

For addressing it, assure the initializations of timer and work by
moving them to the beginning of podhd_init().

Fixes: 790869dacc3d ("ALSA: line6: Add support for POD X3")
Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
Tested-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/usb/line6/podhd.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/sound/usb/line6/podhd.c
+++ b/sound/usb/line6/podhd.c
@@ -307,6 +307,9 @@ static int podhd_init(struct usb_line6 *

 	line6->disconnect = podhd_disconnect;

+	init_timer(&pod->startup_timer);
+	INIT_WORK(&pod->startup_work, podhd_startup_workqueue);
+
 	if (pod->line6.properties->capabilities & LINE6_CAP_CONTROL) {
 		/* create sysfs entries: */
 		err = snd_card_add_dev_attr(line6->card, &podhd_dev_attr_group);
@@ -330,8 +333,6 @@ static int podhd_init(struct usb_line6 *
 	}

 	/* init device and delay registering */
-	init_timer(&pod->startup_timer);
-	INIT_WORK(&pod->startup_work, podhd_startup_workqueue);
 	podhd_startup(pod);
 	return 0;
 }