[PATCH 4.9 241/251] parisc: led: Fix potential null-ptr-deref in start_task()

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From: Shang XiaoJing <shangxiaojing@xxxxxxxxxx>

commit 41f563ab3c33698bdfc3403c7c2e6c94e73681e4 upstream.

start_task() calls create_singlethread_workqueue() and not checked the
ret value, which may return NULL. And a null-ptr-deref may happen:

start_task()
    create_singlethread_workqueue() # failed, led_wq is NULL
    queue_delayed_work()
        queue_delayed_work_on()
            __queue_delayed_work()  # warning here, but continue
                __queue_work()      # access wq->flags, null-ptr-deref

Check the ret value and return -ENOMEM if it is NULL.

Fixes: 3499495205a6 ("[PARISC] Use work queue in LED/LCD driver instead of tasklet.")
Signed-off-by: Shang XiaoJing <shangxiaojing@xxxxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/parisc/led.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -141,6 +141,9 @@ static int start_task(void)
 
 	/* Create the work queue and queue the LED task */
 	led_wq = create_singlethread_workqueue("led_wq");	
+	if (!led_wq)
+		return -ENOMEM;
+
 	queue_delayed_work(led_wq, &led_task, 0);
 
 	return 0;





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