[alsa-devel] usb/sound/line6: trying to register non-static key in podhd_disconnect

[Takashi Iwai]

On Mon, 09 Oct 2017 12:58:59 +0200,
Andrey Konovalov wrote:
> 
> On Tue, Oct 3, 2017 at 9:41 AM, Takashi Iwai <tiwai at suse.de> wrote:
> > On Mon, 25 Sep 2017 14:40:08 +0200,
> > Andrey Konovalov wrote:
> >>
> >> Hi!
> >>
> >> I've got the following report while fuzzing the kernel with syzkaller.
> >>
> >> On commit e19b205be43d11bff638cad4487008c48d21c103 (4.14-rc2).
> >>
> >> 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
> >>  usb_probe_interface+0x35d/0x8e0 drivers/usb/core/driver.c:361
> >>  really_probe drivers/base/dd.c:413
> >>  driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> >>  __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> >>  bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> >>  __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> >>  device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> >>  bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> >>  device_add+0xd0b/0x1660 drivers/base/core.c:1835
> >>  usb_set_configuration+0x104e/0x1870 drivers/usb/core/message.c:1932
> >>  generic_probe+0x73/0xe0 drivers/usb/core/generic.c:174
> >>  usb_probe_device+0xaf/0xe0 drivers/usb/core/driver.c:266
> >>  really_probe drivers/base/dd.c:413
> >>  driver_probe_device+0x610/0xa00 drivers/base/dd.c:557
> >>  __device_attach_driver+0x230/0x290 drivers/base/dd.c:653
> >>  bus_for_each_drv+0x161/0x210 drivers/base/bus.c:463
> >>  __device_attach+0x26e/0x3d0 drivers/base/dd.c:710
> >>  device_initial_probe+0x1f/0x30 drivers/base/dd.c:757
> >>  bus_probe_device+0x1eb/0x290 drivers/base/bus.c:523
> >>  device_add+0xd0b/0x1660 drivers/base/core.c:1835
> >>  usb_new_device+0x7b8/0x1020 drivers/usb/core/hub.c:2457
> >>  hub_port_connect drivers/usb/core/hub.c:4903
> >>  hub_port_connect_change drivers/usb/core/hub.c:5009
> >>  port_event drivers/usb/core/hub.c:5115
> >>  hub_event+0x194d/0x3740 drivers/usb/core/hub.c:5195
> >>  process_one_work+0xc7f/0x1db0 kernel/workqueue.c:2119
> >>  worker_thread+0x221/0x1850 kernel/workqueue.c:2253
> >>  kthread+0x3a1/0x470 kernel/kthread.c:231
> >>  ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
> >
> > This looks like an access to the uninitialized timer object.
> > Could you check the patch below whether it fixes the issue?
> > Thanks!
> >
> >
> > Takashi
> 
> Hi Takashi,
> 
> I've applied your patch and now get GPF on
> usb_driver_release_interface(&podhd_driver, intf):

Another day, another Oops...  The patch below should cover it.
I'm going to queue both now.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai at suse.de>
Subject: [PATCH] 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 at google.com>
Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/usb/line6/podhd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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);
 	}
 }
 
-- 
2.14.2