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workqueue: Only unregister a registered lockdep key 

The recent change to prevent use after free and a memory leak introduced an
unconditional call to wq_unregister_lockdep() in the error handling
path. If the lockdep key had not been registered yet, then the lockdep core
emits a warning.

Only call wq_unregister_lockdep() if wq_register_lockdep() has been
called first.

Fixes: 009bb421b6 ("workqueue, lockdep: Fix an alloc_workqueue() error path")
Reported-by: syzbot+be0c198232f86389c3dd@syzkaller.appspotmail.com
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Qian Cai <cai@lca.pw>
Link: https://lkml.kernel.org/r/20190311230255.176081-1-bvanassche@acm.org
This commit is contained in:
Bart Van Assche 2019-03-11 16:02:55 -07:00 committed by Thomas Gleixner
parent 9e98c678c2
commit 82efcab3b9
1 changed files with 3 additions and 2 deletions
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5
kernel/workqueue.c
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@ -4266,7 +4266,7 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
INIT_LIST_HEAD(&wq->list);
if (alloc_and_link_pwqs(wq) < 0)
goto err_free_wq;
goto err_unreg_lockdep;
if (wq_online && init_rescuer(wq) < 0)
goto err_destroy;
@ -4292,9 +4292,10 @@ struct workqueue_struct *alloc_workqueue(const char *fmt,
return wq;
err_free_wq:
err_unreg_lockdep:
wq_unregister_lockdep(wq);
wq_free_lockdep(wq);
err_free_wq:
free_workqueue_attrs(wq->unbound_attrs);
kfree(wq);
return NULL;