linux-kernel - Re: [PATCH v2 2/2] firmware: qcom: qcom

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Message-ID: <f46a9180-ca71-458e-9693-ed9badc85e72@quicinc.com>
Date: Wed, 16 Oct 2024 14:31:51 +0530
From: Kuldeep Singh <quic_kuldsing@...cinc.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
CC: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konradybcio@...nel.org>,
        Bartosz Golaszewski
	<bartosz.golaszewski@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] firmware: qcom: qcom_tzmem: Implement sanity
 checks


On 10/14/2024 6:38 PM, Bartosz Golaszewski wrote:
> On Mon, Oct 14, 2024 at 1:19 PM Kuldeep Singh <quic_kuldsing@...cinc.com> 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@...cinc.com>
>> ---
>>  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

> 
>> +
>>         switch (config->policy) {
>>         case QCOM_TZMEM_POLICY_STATIC:
>>                 if (!config->initial_size)
>> @@ -412,6 +415,9 @@ void qcom_tzmem_free(void *vaddr)
>>  {
>>         struct qcom_tzmem_chunk *chunk;
>>
>> +       if (!vaddr)
>> +               return;
>> +
>>         scoped_guard(spinlock_irqsave, &qcom_tzmem_chunks_lock)
>>                 chunk = radix_tree_delete_item(&qcom_tzmem_chunks,
>>                                                (unsigned long)vaddr, NULL);
> 
> This would lead to a WARN() as the lookup would inevitably fail. We
> can possibly keep this bit but please change the commit message.

Sure, will reword commit message.

-- 
Regards
Kuldeep