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    Subject[PATCH 5.3 156/344] media: cec-notifier: clear cec_adap in cec_notifier_unregister
    Date
    From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

    [ Upstream commit 14d5511691e5290103bc480998bc322e68f139d4 ]

    If cec_notifier_cec_adap_unregister() is called before
    cec_unregister_adapter() then everything is OK (and this is the
    case today). But if it is the other way around, then
    cec_notifier_unregister() is called first, and that doesn't
    set n->cec_adap to NULL.

    So if e.g. cec_notifier_set_phys_addr() is called after
    cec_notifier_unregister() but before cec_unregister_adapter()
    then n->cec_adap points to an unregistered and likely deleted
    cec adapter. So just set n->cec_adap->notifier and n->cec_adap
    to NULL for rubustness.

    Eventually cec_notifier_unregister will disappear and this will
    be simplified substantially.

    Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
    Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/media/cec/cec-notifier.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/media/cec/cec-notifier.c b/drivers/media/cec/cec-notifier.c
    index 52a867bde15fd..4d82a5522072e 100644
    --- a/drivers/media/cec/cec-notifier.c
    +++ b/drivers/media/cec/cec-notifier.c
    @@ -218,6 +218,8 @@ void cec_notifier_unregister(struct cec_notifier *n)

    mutex_lock(&n->lock);
    n->callback = NULL;
    + n->cec_adap->notifier = NULL;
    + n->cec_adap = NULL;
    mutex_unlock(&n->lock);
    cec_notifier_put(n);
    }
    --
    2.20.1


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