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Subject[PATCH] media: hdpvr: call flush_work only if initialized
Date
From: Dongliang Mu <mudongliangabcd@gmail.com>

flush_work will throw one WARN if worker->func is NULL. So we should always
initialize one worker before calling flush_work. When hdpvr_probe does not
initialize its worker, the hdpvr_disconnect will encounter one WARN. The
stack trace is in the following:

hdpvr_disconnect+0xb8/0xf2 drivers/media/usb/hdpvr/hdpvr-core.c:425
usb_unbind_interface+0xbf/0x3a0 drivers/usb/core/driver.c:458
__device_release_driver drivers/base/dd.c:1206 [inline]
device_release_driver_internal+0x22a/0x230 drivers/base/dd.c:1237
bus_remove_device+0x108/0x160 drivers/base/bus.c:529
device_del+0x1fe/0x510 drivers/base/core.c:3592
usb_disable_device+0xd1/0x1d0 drivers/usb/core/message.c:1419
usb_disconnect+0x109/0x330 drivers/usb/core/hub.c:2228

Fix this by adding a sanity check of the worker before flush_work.

Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Dongliang Mu <mudongliangabcd@gmail.com>
---
drivers/media/usb/hdpvr/hdpvr-core.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/hdpvr/hdpvr-core.c b/drivers/media/usb/hdpvr/hdpvr-core.c
index 52e05a69c46e..d102b459d45d 100644
--- a/drivers/media/usb/hdpvr/hdpvr-core.c
+++ b/drivers/media/usb/hdpvr/hdpvr-core.c
@@ -422,7 +422,8 @@ static void hdpvr_disconnect(struct usb_interface *interface)
mutex_unlock(&dev->io_mutex);
v4l2_device_disconnect(&dev->v4l2_dev);
msleep(100);
- flush_work(&dev->worker);
+ if (dev->worker.func)
+ flush_work(&dev->worker);
mutex_lock(&dev->io_mutex);
hdpvr_cancel_queue(dev);
mutex_unlock(&dev->io_mutex);
--
2.25.1
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