[PATCH 4.4 39/47] uwb: properly check kthread_run return value

From: Greg Kroah-Hartman
Date: Tue Oct 10 2017 - 15:54:23 EST


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

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

From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

commit bbf26183b7a6236ba602f4d6a2f7cade35bba043 upstream.

uwbd_start() calls kthread_run() and checks that the return value is
not NULL. But the return value is not NULL in case kthread_run() fails,
it takes the form of ERR_PTR(-EINTR).

Use IS_ERR() instead.

Also add a check to uwbd_stop().

Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/uwb/uwbd.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/uwb/uwbd.c
+++ b/drivers/uwb/uwbd.c
@@ -303,18 +303,22 @@ static int uwbd(void *param)
/** Start the UWB daemon */
void uwbd_start(struct uwb_rc *rc)
{
- rc->uwbd.task = kthread_run(uwbd, rc, "uwbd");
- if (rc->uwbd.task == NULL)
+ struct task_struct *task = kthread_run(uwbd, rc, "uwbd");
+ if (IS_ERR(task)) {
+ rc->uwbd.task = NULL;
printk(KERN_ERR "UWB: Cannot start management daemon; "
"UWB won't work\n");
- else
+ } else {
+ rc->uwbd.task = task;
rc->uwbd.pid = rc->uwbd.task->pid;
+ }
}

/* Stop the UWB daemon and free any unprocessed events */
void uwbd_stop(struct uwb_rc *rc)
{
- kthread_stop(rc->uwbd.task);
+ if (rc->uwbd.task)
+ kthread_stop(rc->uwbd.task);
uwbd_flush(rc);
}