Re: [PATCH v2 2/2] firmware: qcom: qcom_tzmem: Implement sanity checks

[Kuldeep Singh]

On 10/22/2024 12:27 PM, Bartosz Golaszewski wrote:
> On Tue, 22 Oct 2024 at 07:43, Kuldeep Singh <quic_kuldsing@xxxxxxxxxxx> wrote:
>>
>>
>>
>> On 10/16/2024 2:31 PM, Kuldeep Singh wrote:
>>>
>>> On 10/14/2024 6:38 PM, Bartosz Golaszewski wrote:
>>>> On Mon, Oct 14, 2024 at 1:19 PM Kuldeep Singh <quic_kuldsing@xxxxxxxxxxx> wrote:
>>>>>
>>>>> The qcom_tzmem driver currently has exposed APIs that lack validations
>>>>> on required input parameters. This oversight can lead to unexpected null
>>>>> pointer dereference crashes.
>>>>>
>>>>
>>>> The commit message is not true. None of the things you changed below
>>>> can lead to a NULL-pointer dereference.>
>>>>> To address this issue, add sanity for required input parameters.
>>>>>
>>>>> Signed-off-by: Kuldeep Singh <quic_kuldsing@xxxxxxxxxxx>
>>>>> ---
>>>>>  drivers/firmware/qcom/qcom_tzmem.c | 6 ++++++
>>>>>  1 file changed, 6 insertions(+)
>>>>>
>>>>> diff --git a/drivers/firmware/qcom/qcom_tzmem.c b/drivers/firmware/qcom/qcom_tzmem.c
>>>>> index 92b365178235..977e48fec32f 100644
>>>>> --- a/drivers/firmware/qcom/qcom_tzmem.c
>>>>> +++ b/drivers/firmware/qcom/qcom_tzmem.c
>>>>> @@ -203,6 +203,9 @@ qcom_tzmem_pool_new(const struct qcom_tzmem_pool_config *config)
>>>>>
>>>>>         might_sleep();
>>>>>
>>>>> +       if (!config->policy)
>>>>> +               return ERR_PTR(-EINVAL);
>>>>
>>>> This is already handled by the default case of the switch.
>>>
>>> Ack. Need to drop.
>>> https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L218
>>>
>>> While examining qcom_tzmem_pool_free under the same principle, it
>>> appears the following check is unnecessary.
>>> https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L268
>>>
>>
>> Bartosz,
>> I am thinking to remove below check in next rev like mentioned above.
>> https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L268
>>
>> Do you have any other opinion here?
>> Please let me know.
>>
> 
> No, let's keep the NULL-pointer check and add it to qcom_tzmem_free(),
> I'm not against it. I was just saying that in the latter case it will
> already be handled by the radix tree lookup.

Hey, I think you misread my comment. Let me explain more.
As agreed, Will drop (!config->policy) check from qcom_tzmem_pool_new
because it's already present.
https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L218

Keep (!vaddr) check in qcom_tzmem_free as discussed above.
https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L411

And last thing, like we don't check (!pool) in qcom_tzmem_alloc as it
cannot be null, same way I believe (!pool) is unnecessary in
qcom_tzmem_pool_free as qcom_tzmem_pool_new should return valid pool and
if not, should be handled by calling driver.
https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L369
https://elixir.bootlin.com/linux/v6.12-rc3/source/drivers/firmware/qcom/qcom_tzmem.c#L268

-- 
Regards
Kuldeep