On Mon, Jun 28, 2021 at 10:57:41PM +0530, Manivannan Sadhasivam wrote:

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 resetting the count value to zero before adding cooling devices.

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

---

Bjorn: I've just compile tested this patch.

drivers/soc/qcom/qcom_aoss.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c index 934fcc4d2b05..98c665411768 100644 --- a/drivers/soc/qcom/qcom_aoss.c +++ b/drivers/soc/qcom/qcom_aoss.c @@ -488,6 +488,7 @@ static int qmp_cooling_devices_register(struct qmp *qmp) if (!qmp->cooling_devs) return -ENOMEM;

• count = 0; for_each_available_child_of_node(np, child) { if (!of_find_property(child, "#cooling-cells", NULL)) continue;

@@ -497,12 +498,16 @@ 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; }

A few more previous lines of code for context:

int count = QMP_NUM_COOLING_RESOURCES;

qmp->cooling_devs = devm_kcalloc(qmp->dev, count, sizeof(*qmp->cooling_devs), GFP_KERNEL);

I would suggest to initialize 'count' to 0 from the start and pass QMP_NUM_COOLING_RESOURCES to devm_kcalloc() rather than 'count', instead of resetting 'count' afterwards.

On Mon 28 Jun 12:27 CDT 2021, Manivannan Sadhasivam wrote:

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 resetting the count value to zero before adding cooling devices.

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

---

Bjorn: I've just compile tested this patch.

drivers/soc/qcom/qcom_aoss.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c index 934fcc4d2b05..98c665411768 100644 --- a/drivers/soc/qcom/qcom_aoss.c +++ b/drivers/soc/qcom/qcom_aoss.c @@ -488,6 +488,7 @@ static int qmp_cooling_devices_register(struct qmp *qmp) if (!qmp->cooling_devs) return -ENOMEM;

• count = 0;

This will address the immediate problem, which is that we assign cooling_devs[2..] in this loop. But, like Matthias I don't think we should use "count" as a constant in the first hunk and then reset it and use it as a counter in the second hunk.

Frankly, I don't see why cooling_devs is dynamically allocated (without being conditional on there being any children).

So, could you please make the cooling_devs an array of size QMP_NUM_COOLING_RESOURCES, remove the dynamic allocation here, just initialize count to 0 and add a check in the loop to generate an error if count == QMP_NUM_COOLING_RESOURCES?

for_each_available_child_of_node(np, child) { if (!of_find_property(child, "#cooling-cells", NULL)) continue; @@ -497,12 +498,16 @@ static int qmp_cooling_devices_register(struct qmp *qmp) goto unroll; }

• if (!count)

• devm_kfree(qmp->dev, qmp->cooling_devs);
  

I presume this is just an optimization, to get some memory back when there's no cooling devices specified in DT. I don't think this is necessary and this made me want the static sizing of the array..

• return 0;

unroll: while (--count >= 0) thermal_cooling_device_unregister (qmp->cooling_devs[count].cdev);

• devm_kfree(qmp->dev, qmp->cooling_devs);

I don't remember why we don't fail probe() when this happens, seems like the DT properties should be optional but the errors adding them should be fatal. But that's a separate issue.

Regards, Bjorn

return ret; } -- 2.25.1