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Message-ID: <720e1ee0-79b0-4d30-b1b8-a90676057161@quicinc.com>
Date: Wed, 17 Apr 2024 15:12:38 +0530
From: Viken Dadhaniya <quic_vdadhani@...cinc.com>
To: Bjorn Andersson <quic_bjorande@...cinc.com>
CC: <andersson@...nel.org>, <konrad.dybcio@...aro.org>,
<srinivas.kandagatla@...aro.org>, <linux-arm-msm@...r.kernel.org>,
<alsa-devel@...a-project.org>, <linux-kernel@...r.kernel.org>,
<quic_msavaliy@...cinc.com>, <quic_vtanuku@...cinc.com>,
<quic_anupkulk@...cinc.com>, <quic_cchiluve@...cinc.com>
Subject: Re: [PATCH v1 RESEND] slimbus: stream: Add null pointer check for
client functions
On 4/11/2024 9:26 PM, Bjorn Andersson wrote:
> On Wed, Mar 27, 2024 at 02:02:14PM +0530, Viken Dadhaniya wrote:
>> There is a possible scenario where client driver is calling
>
> How can we asses the validity or the risk of this problem?
> How would I know if this matches e.g. a bug report reported by a user?
>
> Describe the problem such that the reviewer can asses the validity and
> severity of your bug fixes.
Ok. Updated commit log in v2
>
>> 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.
>>
>
> You use the work "fix" a few time, are you fixing an actual bug? Are you
> just guarding the driver from incorrect usage?
>
> If it's a fix, then add Fixes and Cc: stable here.
Let me correct myself there. Not a fix but consider an improvement where
preventing a crash due to client following the incorrect sequence.
>
>> Signed-off-by: Viken Dadhaniya <quic_vdadhani@...cinc.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__);
>
> Use dev_err() and write your error messages such that they make sense
> without the use of __func__.
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 any concern with pr_err
>
>> + return -EINVAL;
>
> Is this expected to happen during normal operation, or is this a sign of
> a bug?
>
It's a scenario where client doesn't follow the proper sequence and
slimbus driver can crash if not checked against NULL.
>
> Neither of the two callers of this function checks the return value, so
> is this really going to result in a good system state?
>
we expect client to check return value of framework APIs.
>
> It would make sense to require the client to pass valid rt and cfg
> pointers, and if you have an issue in the client driver in which we
> might end up with invalid points, then those drivers should be fixed -
> rather than relying on chance and swipe it under the rug here.
>
> Regards,
> Bjorn
>
Agree. it is sequence mismatch from client driver, and they should take
care. it is leading to NULL pointer access in slimbus APIs, so prevent
crash by adding check.
>> + }
>> +
>> + 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);
>> --
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
>> of Code Aurora Forum, hosted by The Linux Foundation
>>
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