Messages in this thread | | | Date | Wed, 17 Apr 2024 15:12:38 +0530 | Subject | Re: [PATCH v1 RESEND] slimbus: stream: Add null pointer check for client functions | From | Viken Dadhaniya <> |
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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@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__); > > 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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