Re: [net-next,v4,9/9] ice: dpll: Support E825-C SyncE and dynamic pin discovery

[Ivan Vecera <ivecera@redhat.com>]

On 2/3/26 5:11 PM, Simon Horman wrote:
> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
> 
> For local reproduction steps seehttps://netdev-ai.bots.linux.dev/ai-local.html
> ---
> ice: dpll: Support E825-C SyncE and dynamic pin discovery
> 
> This patch implements SyncE support for the E825-C Ethernet controller
> using the DPLL subsystem, with dynamic pin discovery via firmware (ACPI)
> and asynchronous registration using the DPLL notifier chain.
> 
>> diff --git a/drivers/net/ethernet/intel/ice/ice_dpll.c b/drivers/net/ethernet/intel/ice/ice_dpll.c
>> index 4eca62688d83..a8c99e49bfae 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_dpll.c
>> +++ b/drivers/net/ethernet/intel/ice/ice_dpll.c
> [ ... ]
> 
>> @@ -528,6 +529,92 @@ ice_dpll_pin_disable(struct ice_hw *hw, struct ice_dpll_pin *pin,
>>   	return ret;
>>   }
>>
>> +/**
>> + * ice_dpll_rclk_update - updates the state of rclk pin on a device
>> + * @pf: private board struct
>> + * @pin: pointer to a pin
>> + * @port_num: port number
>> + *
>> + * Update struct holding pin states info, states are separate for each parent
>> + *
>> + * Context: Called under pf->dplls.lock
>> + * Return:
>> + * * 0 - OK
>> + * * negative - error
>> + */
>> +static int ice_dpll_rclk_update(struct ice_pf *pf, struct ice_dpll_pin *pin,
>> +				u8 port_num)
>> +{
>> +	int ret;
>> +
>> +	for (u8 parent = 0; parent < pf->dplls.rclk.num_parents; parent++) {
>> +		ret = ice_aq_get_phy_rec_clk_out(&pf->hw, &parent, &port_num,
>> +						 &pin->flags[parent], NULL);
> Is it safe to pass &parent as an output parameter when it's also the loop
> counter? Looking at ice_aq_get_phy_rec_clk_out():
> 
>      int ice_aq_get_phy_rec_clk_out(struct ice_hw *hw, u8 *phy_output, ...)
>      {
>          cmd->phy_output = *phy_output;  // Read as input
>          status = ice_aq_send_cmd(hw, &desc, NULL, 0, NULL);
>          if (!status) {
>              *phy_output = cmd->phy_output;  // Write back from firmware
>          ...
> 
> The firmware could potentially return a different value than was sent,
> which would be written back to 'parent', corrupting the loop counter.
> 
> This corrupted value is then used as an array index:
> 
>> +		if (ret)
>> +			return ret;
>> +
>> +		ice_dpll_pin_store_state(pin, parent,
>> +					 ICE_AQC_GET_PHY_REC_CLK_OUT_OUT_EN &
>> +					 pin->flags[parent]);
> Both pin->flags[parent] and pin->state[parent] (inside
> ice_dpll_pin_store_state) could access out of bounds if firmware returns
> a value >= ICE_DPLL_RCLK_NUM_MAX (which is 2).
> 
> Would it be safer to use a separate variable for the phy_output parameter
> and validate that firmware echoes back the expected value?

Yes, there should be a separate variable like in previous code prior
this refactor...

<snip>
         case ICE_DPLL_PIN_TYPE_RCLK_INPUT:
-               for (parent = 0; parent < pf->dplls.rclk.num_parents;
-                    parent++) {
-                       u8 p = parent; <--- HERE
-
-                       ret = ice_aq_get_phy_rec_clk_out(&pf->hw, &p,
-                                                        &port_num,
- 
&pin->flags[parent],
-                                                        NULL);
</snip>

Arek, I will fix it by myself.

Thanks,
Ivan