[PATCH v2] soc: qcom: aoss: Fix the out of bound usage of cooling_devs

[PATCH v2] soc: qcom: aoss: Fix the out of bound usage of cooling_devs

[Manivannan Sadhasivam]

In "qmp_cooling_devices_register", the count value is initially
QMP_NUM_COOLING_RESOURCES, which is 2. Based on the initial count value,
the memory for cooling_devs is allocated. Then while calling the
"qmp_cooling_device_add" function, count value is post-incremented for
each child node.

This makes the out of bound access to the cooling_dev array. Fix it by
passing the QMP_NUM_COOLING_RESOURCES definition to devm_kzalloc() and
initializing the count to 0.

While at it, let's also free the memory allocated to cooling_dev if no
cooling device is found in DT and during unroll phase.

Cc: stable@vger.kernel.org # 5.4
Fixes: 05589b30b21a ("soc: qcom: Extend AOSS QMP driver to support resources that are used to wake up the SoC.")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---

Changes in v2:

* Used QMP_NUM_COOLING_RESOURCES directly and initialized count to 0

 drivers/soc/qcom/qcom_aoss.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
index 934fcc4d2b05..7b6b94332510 100644
--- a/drivers/soc/qcom/qcom_aoss.c
+++ b/drivers/soc/qcom/qcom_aoss.c
@@ -476,12 +476,12 @@ static int qmp_cooling_device_add(struct qmp *qmp,
 static int qmp_cooling_devices_register(struct qmp *qmp)
 {
 	struct device_node *np, *child;
-	int count = QMP_NUM_COOLING_RESOURCES;
+	int count = 0;
 	int ret;
 
 	np = qmp->dev->of_node;
 
-	qmp->cooling_devs = devm_kcalloc(qmp->dev, count,
+	qmp->cooling_devs = devm_kcalloc(qmp->dev, QMP_NUM_COOLING_RESOURCES,
 					 sizeof(*qmp->cooling_devs),
 					 GFP_KERNEL);
 
@@ -497,12 +497,16 @@ static int qmp_cooling_devices_register(struct qmp *qmp)
 			goto unroll;
 	}
 
+	if (!count)
+		devm_kfree(qmp->dev, qmp->cooling_devs);
+
 	return 0;
 
 unroll:
 	while (--count >= 0)
 		thermal_cooling_device_unregister
 			(qmp->cooling_devs[count].cdev);
+	devm_kfree(qmp->dev, qmp->cooling_devs);
 
 	return ret;
 }
-- 
2.25.1