[PATCH v1] slimbus: stream: Add null pointer check to prevent crash

[Viken Dadhaniya <quic_vdadhani@xxxxxxxxxxx>]

We are facing crash due to null pointer dereference of stream
in slim_stream_disable(). there is a possible scenario where
client driver is calling slimbus stream APIs in incorrect
sequence and it might lead to null pointer access of the stream
in slimbus enable/disable/prepare/unprepare/free functions.

Fix this issue by adding null pointer check of the stream before
accessing in all stream API’s exposed to client.

Signed-off-by: Viken Dadhaniya <quic_vdadhani@xxxxxxxxxxx>
---
 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__);
+		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);
-- 
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