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    Subject[PATCH 4.19 055/100] workqueue: Try to catch flush_work() without INIT_WORK().
    Date
    From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>

    commit 4d43d395fed124631ca02356c711facb90185175 upstream.

    syzbot found a flush_work() caller who forgot to call INIT_WORK()
    because that work_struct was allocated by kzalloc() [1]. But the message

    INFO: trying to register non-static key.
    the code is fine but needs lockdep annotation.
    turning off the locking correctness validator.

    by lock_map_acquire() is failing to tell that INIT_WORK() is missing.

    Since flush_work() without INIT_WORK() is a bug, and INIT_WORK() should
    set ->func field to non-zero, let's warn if ->func field is zero.

    [1] https://syzkaller.appspot.com/bug?id=a5954455fcfa51c29ca2ab55b203076337e1c770

    Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Signed-off-by: Tejun Heo <tj@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    kernel/workqueue.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/kernel/workqueue.c
    +++ b/kernel/workqueue.c
    @@ -2908,6 +2908,9 @@ static bool __flush_work(struct work_str
    if (WARN_ON(!wq_online))
    return false;

    + if (WARN_ON(!work->func))
    + return false;
    +
    if (!from_cancel) {
    lock_map_acquire(&work->lockdep_map);
    lock_map_release(&work->lockdep_map);

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