Re: [PATCH v1 RESEND] slimbus: stream: Add null pointer check for client functions

[Viken Dadhaniya <quic_vdadhani@quicinc.com>]

On 4/11/2024 3:19 PM, Srinivas Kandagatla wrote:
> Thanks Viken for the patch,
> 
> On 27/03/2024 08:32, Viken Dadhaniya wrote:
>> There is a possible scenario where client driver is calling
>> slimbus stream APIs in incorrect sequence and it might lead to
>> invalid null access of the stream pointer in slimbus
>> enable/disable/prepare/unprepare/free function.
>>
>> Fix this by checking validity of the stream before accessing in
>> all function API’s exposed to client.
>>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@quicinc.com>
>> ---
>>   drivers/slimbus/stream.c | 37 +++++++++++++++++++++++++++++++++----
>>   1 file changed, 33 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/slimbus/stream.c b/drivers/slimbus/stream.c
>> index 1d6b38657917..c5a436fd0952 100644
>> --- a/drivers/slimbus/stream.c
>> +++ b/drivers/slimbus/stream.c
>> @@ -202,10 +202,16 @@ static int slim_get_prate_code(int rate)
>>   int slim_stream_prepare(struct slim_stream_runtime *rt,
>>               struct slim_stream_config *cfg)
>>   {
>> -    struct slim_controller *ctrl = rt->dev->ctrl;
>> +    struct slim_controller *ctrl;
>>       struct slim_port *port;
>>       int num_ports, i, port_id, prrate;
>> +    if (!rt || !cfg) {
>> +        pr_err("%s: Stream or cfg is NULL, Check from client side\n", 
>> __func__);
> 
> Please use dev_err where possible
> 
> 
> --srini


For error scenario, we don't have valid dev to be used in dev_err 
argument. this log will help for debug.
Please let us know if any concern with pr_err.


>> +        return -EINVAL;
>> +    }
>> +
>> +    ctrl = rt->dev->ctrl;
>>       if (rt->ports) {
>>           dev_err(&rt->dev->dev, "Stream already Prepared\n");
>>           return -EINVAL;
>> @@ -358,9 +364,15 @@ int slim_stream_enable(struct slim_stream_runtime 
>> *stream)
>>   {
>>       DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION,
>>                   3, SLIM_LA_MANAGER, NULL);
>> -    struct slim_controller *ctrl = stream->dev->ctrl;
>> +    struct slim_controller *ctrl;
>>       int ret, i;
>> +    if (!stream) {
>> +        pr_err("%s: Stream is NULL, Check from client side\n", 
>> __func__);
>> +        return -EINVAL;
>> +    }
>> +
>> +    ctrl = stream->dev->ctrl;
>>       if (ctrl->enable_stream) {
>>           ret = ctrl->enable_stream(stream);
>>           if (ret)
>> @@ -411,12 +423,18 @@ int slim_stream_disable(struct 
>> slim_stream_runtime *stream)
>>   {
>>       DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION,
>>                   3, SLIM_LA_MANAGER, NULL);
>> -    struct slim_controller *ctrl = stream->dev->ctrl;
>> +    struct slim_controller *ctrl;
>>       int ret, i;
>> +    if (!stream) {
>> +        pr_err("%s: Stream is NULL, Check from client side\n", 
>> __func__);
>> +        return -EINVAL;
>> +    }
>> +
>>       if (!stream->ports || !stream->num_ports)
>>           return -EINVAL;
>> +    ctrl = stream->dev->ctrl;
>>       if (ctrl->disable_stream)
>>           ctrl->disable_stream(stream);
>> @@ -448,6 +466,11 @@ int slim_stream_unprepare(struct 
>> slim_stream_runtime *stream)
>>   {
>>       int i;
>> +    if (!stream) {
>> +        pr_err("%s: Stream is NULL, Check from client side\n", 
>> __func__);
>> +        return -EINVAL;
>> +    }
>> +
>>       if (!stream->ports || !stream->num_ports)
>>           return -EINVAL;
>> @@ -476,8 +499,14 @@ EXPORT_SYMBOL_GPL(slim_stream_unprepare);
>>    */
>>   int slim_stream_free(struct slim_stream_runtime *stream)
>>   {
>> -    struct slim_device *sdev = stream->dev;
>> +    struct slim_device *sdev;
>> +
>> +    if (!stream) {
>> +        pr_err("%s: Stream is NULL, Check from client side\n", 
>> __func__);
>> +        return -EINVAL;
>> +    }
>> +    sdev = stream->dev;
>>       spin_lock(&sdev->stream_list_lock);
>>       list_del(&stream->node);
>>       spin_unlock(&sdev->stream_list_lock);