Re: [PATCH v3 1/5] soc: qcom: Introduce QMI encoder/decoder

[Chris Lew]

On 11/15/2017 9:42 PM, Bjorn Andersson wrote:
> On Wed 15 Nov 12:10 PST 2017, Bjorn Andersson wrote:
> > diff --git a/drivers/soc/qcom/qmi_encdec.c b/drivers/soc/qcom/qmi_encdec.c
> [..]
> > +void *qmi_encode_message(int type, unsigned int msg_id, size_t *len,
> > +			 unsigned int txn_id, struct qmi_elem_info *ei,
> > +			 const void *c_struct)
> > +{
> > +	struct qmi_header *hdr;
> > +	ssize_t msglen = 0;
> > +	void *msg;
> > +	int ret;
> > +
> > +	/* Check the possibility of a zero length QMI message */
> > +	if (!c_struct) {
> > +		ret = qmi_calc_min_msg_len(ei, 1);
> > +		if (ret) {
> > +			pr_err("%s: Calc. len %d != 0, but NULL c_struct\n",
> > +			       __func__, ret);
> > +			return ERR_PTR(-EINVAL);
> > +		}
> > +	}
> > +
> > +	msg = kzalloc(sizeof(*hdr) + *len, GFP_KERNEL);
> > +	if (!msg)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	msglen = qmi_encode(ei, msg + sizeof(*hdr), c_struct, *len, 1);
> > +	if (msglen < 0) {
> > +		kfree(msg);
> > +		return ERR_PTR(msglen);
> > +	}
>
> Talked to Chris Lew about this earlier today;
>
> The check above implies that it's valid to call this function with a
> valid ei of minimum message length of 0 and c_struct being NULL. But the
> call to qmi_encdec() will dereference c_struct in order to know that the
> optional elements described in ei are unset.
>
> So the call to qmi_encode() needs to only be done conditionally on
> c_struct being non-NULL, logically interpreting c_struct being NULL as
> all optional fields are unset.
>
> Will post an update with this fixed.

I have tested this patch with QMI loopback servers, Qualcomm diag and 
slimbus ngd.

Tested-By: Chris Lew <clew@xxxxxxxxxxxxxx>
> > +
> > +	hdr = msg;
> > +	hdr->type = type;
> > +	hdr->txn_id = txn_id;
> > +	hdr->msg_id = msg_id;
> > +	hdr->msg_len = msglen;
> > +
> > +	*len = sizeof(*hdr) + msglen;
> > +
> > +	return msg;
> > +}
> > +EXPORT_SYMBOL(qmi_encode_message);
>
> Regards,
> Bjorn

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