linux-kernel - Re: [PATCH net] ice: Fix freeing uninitialized pointers

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Message-ID: <4b8ee072-70bc-4a0a-8e43-e244f8ee2f22@web.de>
Date: Wed, 20 Mar 2024 13:18:33 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 kernel-janitors@...r.kernel.org, netdev@...r.kernel.org,
 intel-wired-lan@...ts.osuosl.org,
 Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
 Przemek Kitszel <przemyslaw.kitszel@...el.com>,
 Tony Nguyen <anthony.l.nguyen@...el.com>
Cc: LKML <linux-kernel@...r.kernel.org>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>,
 Jesse Brandeburg <jesse.brandeburg@...el.com>, Jiri Pirko
 <jiri@...nulli.us>, Paolo Abeni <pabeni@...hat.com>,
 Pucha Himasekhar Reddy <himasekharx.reddy.pucha@...el.com>
Subject: Re: [PATCH net] ice: Fix freeing uninitialized pointers

> Automatically cleaned up pointers need to be initialized before exiting
> their scope.  In this case, they need to be initialized to NULL before
> any return statement.

I suggest to reconsider such information a bit more.

…
> +++ b/drivers/net/ethernet/intel/ice/ice_common.c
> @@ -1002,8 +1002,8 @@ static void ice_get_itr_intrl_gran(struct ice_hw *hw)
>   */
>  int ice_init_hw(struct ice_hw *hw)
>  {
> -	struct ice_aqc_get_phy_caps_data *pcaps __free(kfree);
> -	void *mac_buf __free(kfree);
> +	struct ice_aqc_get_phy_caps_data *pcaps __free(kfree) = NULL;
> +	void *mac_buf __free(kfree) = NULL;
>  	u16 mac_buf_len;
>  	int status;

How do you think about to reduce the scope for affected local variables instead
with the help of a small script (like the following) for the semantic patch language?

@movement1@
attribute name __free;
@@
-struct ice_aqc_get_phy_caps_data *pcaps __free(kfree);
 ... when any
+struct ice_aqc_get_phy_caps_data *
 pcaps
+__free(kfree)
 = kzalloc(sizeof(*pcaps), ...);

@movement2@
attribute name __free;
@@
-void *mac_buf __free(kfree);
 ... when any
+void *
 mac_buf
+__free(kfree)
 = kcalloc(2, sizeof(struct ice_aqc_manage_mac_read_resp), ...);

Regards,
Markus