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
-- 8< -- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: line6: Fix missing initialization before error path
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@google.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/line6/podhd.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/sound/usb/line6/podhd.c b/sound/usb/line6/podhd.c index 956f847a96e4..14ab82ea7e82 100644 --- a/sound/usb/line6/podhd.c +++ b/sound/usb/line6/podhd.c @@ -317,6 +317,9 @@ static int podhd_init(struct usb_line6 *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) { /* claim the data interface */ intf = usb_ifnum_to_if(line6->usbdev, @@ -358,8 +361,6 @@ static int podhd_init(struct usb_line6 *line6, }
/* init device and delay registering */ - init_timer(&pod->startup_timer); - INIT_WORK(&pod->startup_work, podhd_startup_workqueue); podhd_startup(pod); return 0; }