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Commit 82efcab3 authored by Bart Van Assche's avatar Bart Van Assche Committed by Thomas Gleixner
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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: 009bb421 ("workqueue, lockdep: Fix an alloc_workqueue() error path")
Reported-by: default avatar <syzbot+be0c198232f86389c3dd@syzkaller.appspotmail.com>
Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Signed-off-by: default avatarThomas 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
parent 9e98c678

kernel/workqueue.c

+3 −2
Original line number Diff line number Diff line
@@ -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;