From: Bjorn Andersson
Sent: 29 June 2021 16:44
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).
Not to mention what happens if there are 3 matching nodes. Given that qmp_cooling_device is only 4 pointers why bother allocating a pointer to it at all. Just instantiate 2 of them in the outer structure. No is going to notice 56 bytes - it is probably hidden in the padding when the outer structure is allocated.
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?
You should set count to 0 just before this loop - not at the top of the function.
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.
David
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