[alsa-devel] [bug report] slimbus: ngd: Add qcom SLIMBus NGD driver

[Srinivas Kandagatla]

Hi Dan,

Thanks for the sharing out this warning msg.

On 07/08/18 13:07, Dan Carpenter wrote:
> Hello Srinivas Kandagatla,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 917809e2280b: "slimbus: ngd: Add qcom SLIMBus NGD driver"
> from Jun 19, 2018, leads to the following Smatch complaint:
> 
>      drivers/slimbus/qcom-ngd-ctrl.c:867 qcom_slim_ngd_xfer_msg()
>       warn: variable dereferenced before check 'txn->msg' (see line 791)
> 
> drivers/slimbus/qcom-ngd-ctrl.c
>     790	
>     791		if (txn->msg->num_bytes > SLIM_MSGQ_BUF_LEN ||
>                      ^^^^^^^^^
> Dereference
> 
>     792				txn->rl > SLIM_MSGQ_BUF_LEN) {
>     793			dev_err(ctrl->dev, "msg exeeds HW limit\n");

...
>     866	
>     867		if (txn->msg && txn->msg->wbuf)
>                      ^^^^^^^^
> This check is too late.

To be honest this function should not be invoked with txn->msg being 
NULL. I can see that slim_val_inf_sanity() enforces this, but we can add 
an additional check in slim_do_transfer() for this not to happen in case 
  slim_do_transfer() is invoked directly.

Check in this ngd driver is totally redundant.
I will try to send a cleanup patch for this once rc1 is out.

thanks,
srini
> 
>     868			memcpy(puc, txn->msg->wbuf, txn->msg->num_bytes);
>     869	
> 
> regards,
> dan carpenter
>