Re: [PATCH] clk: qcom: rcg2: validate frequency table entry in __clk_rcg2_shared_set_rate()

[Gabor Juhos <j4g8y7@gmail.com>]

2026. 10. 27. 19:24 keltezéssel, Taniya Das írta:
> 
> 
> On 10/27/2026 11:35 PM, Gabor Juhos wrote:
>> Commit aec8c0e28ce4 ("clk: qcom: rcg2: add clk_rcg2_shared_floor_ops")
>> removed validating of the frequency table entry pointer returned by the
>> qcom_find_freq() or the qcom_find_freq_floor() functions.
>>
>> Since both functions can return NULL and the pointer is passed directly
>> to the __clk_rcg2_configure() function where it gets dereferenced
>> unconditionally, it could cause a panic.
>>
>> Restore the sanity check removed by the mentioned commit in order to avoid
>> a possible NULL pointer dereference.
>>
>> Compile tested only.
>>
>> Fixes: aec8c0e28ce4 ("clk: qcom: rcg2: add clk_rcg2_shared_floor_ops")
>> Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
>> ---
>>  drivers/clk/qcom/clk-rcg2.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/clk/qcom/clk-rcg2.c b/drivers/clk/qcom/clk-rcg2.c
>> index d7914e59129f..260e90f53461 100644
>> --- a/drivers/clk/qcom/clk-rcg2.c
>> +++ b/drivers/clk/qcom/clk-rcg2.c
>> @@ -1385,6 +1385,9 @@ static int __clk_rcg2_shared_set_rate(struct clk_hw *hw, unsigned long rate,
>>  		return -EINVAL;
>>  	}
>>  
>> +	if (!f)
>> +		return -EINVAL;
>> +
> 
> Normally, the CCF calls .determine_rate before .set_rate. The floor
> determination helper already rejects a request below the lowest supported
>  frequency:
> 
>  ```c
>    if (!f)
>       return -EINVAL;
>  ```
> 
> So an ordinary clk_set_rate() request below the table minimum should
> fail during rate determination and typically not reach
>  __clk_rcg2_shared_set_rate().
> 
> 

Thank you for the explanation, it makes sense.
In this case, we don't need the patch.

Regards,
Gabor