Re: [patch net] dpll: sanitize possible null pointer dereference in dpll_pin_parent_pin_set()

[Vadim Fedorenko <vadim.fedorenko@linux.dev>]

On 11/12/2023 11:43, Jiri Pirko wrote:
> Mon, Dec 11, 2023 at 11:46:24AM CET, vadim.fedorenko@linux.dev wrote:
>> On 11/12/2023 08:37, Jiri Pirko wrote:
>>> From: Jiri Pirko <jiri@nvidia.com>
>>>
>>> User may not pass DPLL_A_PIN_STATE attribute in the pin set operation
>>> message. Sanitize that by checking if the attr pointer is not null
>>> and process the passed state attribute value only in that case.
>>>
>>> Reported-by: Xingyuan Mo <hdthky0@gmail.com>
>>> Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
>>> Signed-off-by: Jiri Pirko <jiri@nvidia.com>
>>> ---
>>>    drivers/dpll/dpll_netlink.c | 13 ++++++++-----
>>>    1 file changed, 8 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
>>> index 442a0ebeb953..ce7cf736f020 100644
>>> --- a/drivers/dpll/dpll_netlink.c
>>> +++ b/drivers/dpll/dpll_netlink.c
>>> @@ -925,7 +925,6 @@ dpll_pin_parent_pin_set(struct dpll_pin *pin, struct nlattr *parent_nest,
>>>    			struct netlink_ext_ack *extack)
>>>    {
>>>    	struct nlattr *tb[DPLL_A_PIN_MAX + 1];
>>> -	enum dpll_pin_state state;
>>>    	u32 ppin_idx;
>>>    	int ret;
>>> @@ -936,10 +935,14 @@ dpll_pin_parent_pin_set(struct dpll_pin *pin, struct nlattr *parent_nest,
>>>    		return -EINVAL;
>>>    	}
>>>    	ppin_idx = nla_get_u32(tb[DPLL_A_PIN_PARENT_ID]);
>>> -	state = nla_get_u32(tb[DPLL_A_PIN_STATE]);
>>> -	ret = dpll_pin_on_pin_state_set(pin, ppin_idx, state, extack);
>>> -	if (ret)
>>> -		return ret;
>>> +
>>> +	if (tb[DPLL_A_PIN_STATE]) {
>>> +		enum dpll_pin_state state = nla_get_u32(tb[DPLL_A_PIN_STATE]);
>>> +
>>> +		ret = dpll_pin_on_pin_state_set(pin, ppin_idx, state, extack);
>>> +		if (ret)
>>> +			return ret;
>>> +	}
>>>    	return 0;
>>>    }
>>
>> I don't believe that "set" command without set value should return 0
>> meaning "request was completed successfully". Maybe it's better to add
>> another check like for DPLL_A_PIN_PARENT_ID and fill extack with
>> description?
> 
> Please see dpll_pin_parent_device_set(). State here is treated exactly
> the same as there. It makes sense during set operation to process only
> the attributes that are passed. In the future, dpll_pin_parent_pin_set()
> can process more attributes, lets be prepared for that.

Ok, let's be ready.

Acked-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>