From: Hans Verkuil <hverkuil-cisco@xs4all.nl> commit 95c29d46ab2a517e4c26d0a07300edca6768db17 upstream. WARN if transmit_queue_sz is 0 but do not decrement it. The CEC adapter will become unresponsive if it goes below 0 since then it thinks there are 4 billion messages in the queue. Obviously this should not happen, but a driver bug could cause this. Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl> Cc: <stable@vger.kernel.org> # for v4.12 and up Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- drivers/media/cec/cec-adap.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/media/cec/cec-adap.c b/drivers/media/cec/cec-adap.c index 913b3ff..16f2181 100644 --- a/drivers/media/cec/cec-adap.c +++ b/drivers/media/cec/cec-adap.c @@ -365,7 +365,8 @@ static void cec_data_cancel(struct cec_data *data, u8 tx_status) } else { list_del_init(&data->list); if (!(data->msg.tx_status & CEC_TX_STATUS_OK)) - data->adap->transmit_queue_sz--; + if (!WARN_ON(!data->adap->transmit_queue_sz)) + data->adap->transmit_queue_sz--; } if (data->msg.tx_status & CEC_TX_STATUS_OK) { @@ -417,6 +418,14 @@ static void cec_flush(struct cec_adapter *adap) * need to do anything special in that case. */ } + /* + * If something went wrong and this counter isn't what it should + * be, then this will reset it back to 0. Warn if it is not 0, + * since it indicates a bug, either in this framework or in a + * CEC driver. + */ + if (WARN_ON(adap->transmit_queue_sz)) + adap->transmit_queue_sz = 0; } /* @@ -507,7 +516,8 @@ int cec_thread_func(void *_adap) data = list_first_entry(&adap->transmit_queue, struct cec_data, list); list_del_init(&data->list); - adap->transmit_queue_sz--; + if (!WARN_ON(!data->adap->transmit_queue_sz)) + adap->transmit_queue_sz--; /* Make this the current transmitting message */ adap->transmitting = data; -- 1.8.3