RE: [Intel-wired-lan] [PATCH net] igb: unregister the i2c adapter when register_netdev() fails

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Linkui Xiao <xiaolinkui@xxxxxxx>
> Sent: Wednesday, September 16, 2026 3:28 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@xxxxxxxxx>; andrew+netdev@xxxxxxx;
> davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx
> Cc: intel-wired-lan@xxxxxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Linkui Xiao <xiaolinkui@xxxxxxxxxx>;
> stable@xxxxxxxxxxxxxxx
> Subject: [Intel-wired-lan] [PATCH net] igb: unregister the i2c adapter
> when register_netdev() fails
> 
> From: Linkui Xiao <xiaolinkui@xxxxxxxxxx>
> 
> igb_probe() sets up the bit-banging i2c adapter with igb_init_i2c()
> before it registers the netdev, but the err_register path only zeroes
> adapter->i2c_adap instead of unregistering the adapter. On i350 parts,
> where igb_init_i2c() really registers the bus, the adapter is
> therefore still registered when free_netdev() releases the memory that
> embeds it.
> The i2c core keeps pointing at the freed adapter, so any later access
> to that bus dereferences freed memory, and the adapter number is
> leaked.
> 
> Call igb_remove_i2c() instead, the same way igb_remove() tears the bus
> down. Move the helper next to igb_init_i2c() so that it is in scope
> for igb_probe(). i2c_del_adapter() returns early for an adapter that
> was never registered, so the parts without i2c support are unaffected.
> 
> Fixes: 441fc6fdb47a ("igb: Add i2c interface to igb.")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Linkui Xiao <xiaolinkui@xxxxxxxxxx>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c
> b/drivers/net/ethernet/intel/igb/igb_main.c
> index d4a897a8c82c..f965ca144f42 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -3190,6 +3190,16 @@ static s32 igb_init_i2c(struct igb_adapter
> *adapter)
>  	return status;
>  }
> 
> +/**
> + *  igb_remove_i2c - Cleanup  I2C interface
> + *  @adapter: pointer to adapter structure  **/ static void
> +igb_remove_i2c(struct igb_adapter *adapter) {
> +	/* free the adapter bus structure */
> +	i2c_del_adapter(&adapter->i2c_adap);
> +}
> +
>  /**
>   *  igb_probe - Device Initialization Routine
>   *  @pdev: PCI device information struct @@ -3657,7 +3667,7 @@ static
> int igb_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
> 
>  err_register:
>  	igb_release_hw_control(adapter);
> -	memset(&adapter->i2c_adap, 0, sizeof(adapter->i2c_adap));
> +	igb_remove_i2c(adapter);
>  err_eeprom:
>  	if (!igb_check_reset_block(hw))
>  		igb_reset_phy(hw);
> @@ -3849,16 +3859,6 @@ static int igb_enable_sriov(struct pci_dev
> *pdev, int num_vfs, bool reinit)  }
> 
>  #endif
> -/**
> - *  igb_remove_i2c - Cleanup  I2C interface
> - *  @adapter: pointer to adapter structure
> - **/
> -static void igb_remove_i2c(struct igb_adapter *adapter) -{
> -	/* free the adapter bus structure */
> -	i2c_del_adapter(&adapter->i2c_adap);
> -}
> -
>  /**
>   *  igb_remove - Device Removal Routine
>   *  @pdev: PCI device information struct
> --
> 2.25.1

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>