Re: [PATCH] resource release cleanup in net/

From: Jesper Juhl
Date: Sat Apr 30 2005 - 18:12:52 EST

On Sun, 1 May 2005, Alexey Dobriyan wrote:

> On Sat, Apr 30, 2005 at 10:36:00PM +0200, Jesper Juhl wrote:
> > Since Andrew merged the patch that makes calling crypto_free_tfm() with a
> > NULL pointer safe into 2.6.12-rc3-mm1, I made a patch to remove checks for
> > NULL before calling that function
> > drivers/net/wireless/hostap/hostap_crypt_ccmp.c | 5 -
> > drivers/net/wireless/hostap/hostap_crypt_tkip.c | 10 +-
> > drivers/net/wireless/hostap/hostap_crypt_wep.c | 5 -
> > net/ieee80211/ieee80211_crypt_ccmp.c | 5 -
> > net/ieee80211/ieee80211_crypt_tkip.c | 10 +-
> > net/ieee80211/ieee80211_crypt_wep.c | 5 -
> I think I have a better one for these.
>
> --- linux-2.6.12-rc3-mm1/drivers/net/wireless/hostap/hostap_crypt_ccmp.c 2005-05-01 01:53:50.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/drivers/net/wireless/hostap/hostap_crypt_ccmp.c 2005-05-01 02:21:10.000000000 +0000
> @@ -102,17 +102,14 @@ static void * hostap_ccmp_init(int key_i
> if (priv->tfm == NULL) {
> printk(KERN_DEBUG "hostap_crypt_ccmp: could not allocate "
> "crypto API aes\n");
> - goto fail;
> + goto fail_free;
> }
>
> return priv;
>
> +fail_free:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm)
> - crypto_free_tfm(priv->tfm);
> - kfree(priv);
> - }
> module_put(THIS_MODULE);
> return NULL;
> }

Personally I find the code a lot simpler when there's just a single label
"fail" that takes care of all the cleanup. But, let's hear what David has
to say on that.


> @@ -121,8 +118,7 @@ fail:
> static void hostap_ccmp_deinit(void *priv)
> {
> struct hostap_ccmp_data *_priv = priv;
> - if (_priv && _priv->tfm)
> - crypto_free_tfm(_priv->tfm);
> + crypto_free_tfm(_priv->tfm);
> kfree(priv);
> module_put(THIS_MODULE);
> }

This will Oops if _priv is NULL. That's why my patch did

if (_priv)
crypto_free_tfm(_priv->tfm);


> --- linux-2.6.12-rc3-mm1/drivers/net/wireless/hostap/hostap_crypt_tkip.c 2005-05-01 01:53:50.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/drivers/net/wireless/hostap/hostap_crypt_tkip.c 2005-05-01 02:27:18.000000000 +0000
> @@ -88,26 +88,23 @@ static void * hostap_tkip_init(int key_i
> if (priv->tfm_arc4 == NULL) {
> printk(KERN_DEBUG "hostap_crypt_tkip: could not allocate "
> "crypto API arc4\n");
> - goto fail;
> + goto fail_arc4;
> }
>
> priv->tfm_michael = crypto_alloc_tfm("michael_mic", 0);
> if (priv->tfm_michael == NULL) {
> printk(KERN_DEBUG "hostap_crypt_tkip: could not allocate "
> "crypto API michael_mic\n");
> - goto fail;
> + goto fail_michael;
> }
>
> return priv;
>
> +fail_michael:
> + crypto_free_tfm(priv->tfm_arc4);
> +fail_arc4:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm_michael)
> - crypto_free_tfm(priv->tfm_michael);
> - if (priv->tfm_arc4)
> - crypto_free_tfm(priv->tfm_arc4);
> - kfree(priv);
> - }
> module_put(THIS_MODULE);
> return NULL;
> }

Again, I find the single 'fail' approach simpler.


> @@ -116,10 +113,8 @@ fail:
> static void hostap_tkip_deinit(void *priv)
> {
> struct hostap_tkip_data *_priv = priv;
> - if (_priv && _priv->tfm_michael)
> - crypto_free_tfm(_priv->tfm_michael);
> - if (_priv && _priv->tfm_arc4)
> - crypto_free_tfm(_priv->tfm_arc4);
> + crypto_free_tfm(_priv->tfm_michael);
> + crypto_free_tfm(_priv->tfm_arc4);
> kfree(priv);
> module_put(THIS_MODULE);
> }

Oops if _priv == NULL.


> --- linux-2.6.12-rc3-mm1/drivers/net/wireless/hostap/hostap_crypt_wep.c 2005-05-01 01:53:50.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/drivers/net/wireless/hostap/hostap_crypt_wep.c 2005-05-01 02:30:08.000000000 +0000
> @@ -59,7 +59,7 @@ static void * prism2_wep_init(int keyidx
> if (priv->tfm == NULL) {
> printk(KERN_DEBUG "hostap_crypt_wep: could not allocate "
> "crypto API arc4\n");
> - goto fail;
> + goto fail_tfm;
> }
>
> /* start WEP IV from a random value */
> @@ -67,12 +67,9 @@ static void * prism2_wep_init(int keyidx
>
> return priv;
>
> +fail_tfm:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm)
> - crypto_free_tfm(priv->tfm);
> - kfree(priv);
> - }
> module_put(THIS_MODULE);
> return NULL;
> }

Again my preference is for the original, same for the rest of these.


> @@ -81,8 +78,7 @@ fail:
> static void prism2_wep_deinit(void *priv)
> {
> struct prism2_wep_data *_priv = priv;
> - if (_priv && _priv->tfm)
> - crypto_free_tfm(_priv->tfm);
> + crypto_free_tfm(_priv->tfm);
> kfree(priv);
> module_put(THIS_MODULE);
> }

Oops if _priv == NULL.


> --- linux-2.6.12-rc3-mm1/net/ieee80211/ieee80211_crypt_ccmp.c 2005-05-01 01:53:57.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/net/ieee80211/ieee80211_crypt_ccmp.c 2005-05-01 02:31:22.000000000 +0000
> @@ -89,18 +89,14 @@ static void * ieee80211_ccmp_init(int ke
> if (priv->tfm == NULL) {
> printk(KERN_DEBUG "ieee80211_crypt_ccmp: could not allocate "
> "crypto API aes\n");
> - goto fail;
> + goto fail_tfm;
> }
>
> return priv;
>
> +fail_tfm:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm)
> - crypto_free_tfm(priv->tfm);
> - kfree(priv);
> - }
> -
> return NULL;
> }
>
> @@ -108,8 +104,7 @@ fail:
> static void ieee80211_ccmp_deinit(void *priv)
> {
> struct ieee80211_ccmp_data *_priv = priv;
> - if (_priv && _priv->tfm)
> - crypto_free_tfm(_priv->tfm);
> + crypto_free_tfm(_priv->tfm);
> kfree(priv);
> }
>
if _priv is NULL this blows up.


> --- linux-2.6.12-rc3-mm1/net/ieee80211/ieee80211_crypt_tkip.c 2005-05-01 01:53:57.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/net/ieee80211/ieee80211_crypt_tkip.c 2005-05-01 02:34:04.000000000 +0000
> @@ -76,27 +76,23 @@ static void * ieee80211_tkip_init(int ke
> if (priv->tfm_arc4 == NULL) {
> printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "
> "crypto API arc4\n");
> - goto fail;
> + goto fail_arc4;
> }
>
> priv->tfm_michael = crypto_alloc_tfm("michael_mic", 0);
> if (priv->tfm_michael == NULL) {
> printk(KERN_DEBUG "ieee80211_crypt_tkip: could not allocate "
> "crypto API michael_mic\n");
> - goto fail;
> + goto fail_michael;
> }
>
> return priv;
>
> +fail_michael:
> + crypto_free_tfm(priv->tfm_arc4);
> +fail_arc4:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm_michael)
> - crypto_free_tfm(priv->tfm_michael);
> - if (priv->tfm_arc4)
> - crypto_free_tfm(priv->tfm_arc4);
> - kfree(priv);
> - }
> -
> return NULL;
> }
>
> @@ -104,10 +100,8 @@ fail:
> static void ieee80211_tkip_deinit(void *priv)
> {
> struct ieee80211_tkip_data *_priv = priv;
> - if (_priv && _priv->tfm_michael)
> - crypto_free_tfm(_priv->tfm_michael);
> - if (_priv && _priv->tfm_arc4)
> - crypto_free_tfm(_priv->tfm_arc4);
> + crypto_free_tfm(_priv->tfm_michael);
> + crypto_free_tfm(_priv->tfm_arc4);
> kfree(priv);
> }
>
Again we'll blow up if _priv is NULL.


> --- linux-2.6.12-rc3-mm1/net/ieee80211/ieee80211_crypt_wep.c 2005-05-01 01:53:57.000000000 +0000
> +++ linux-2.6.12-rc3-mm1-hostap/net/ieee80211/ieee80211_crypt_wep.c 2005-05-01 02:35:18.000000000 +0000
> @@ -54,7 +54,7 @@ static void * prism2_wep_init(int keyidx
> if (priv->tfm == NULL) {
> printk(KERN_DEBUG "ieee80211_crypt_wep: could not allocate "
> "crypto API arc4\n");
> - goto fail;
> + goto fail_tfm;
> }
>
> /* start WEP IV from a random value */
> @@ -62,12 +62,9 @@ static void * prism2_wep_init(int keyidx
>
> return priv;
>
> +fail_tfm:
> + kfree(priv);
> fail:
> - if (priv) {
> - if (priv->tfm)
> - crypto_free_tfm(priv->tfm);
> - kfree(priv);
> - }
> return NULL;
> }
>
> @@ -75,8 +72,7 @@ fail:
> static void prism2_wep_deinit(void *priv)
> {
> struct prism2_wep_data *_priv = priv;
> - if (_priv && _priv->tfm)
> - crypto_free_tfm(_priv->tfm);
> + crypto_free_tfm(_priv->tfm);
> kfree(priv);
> }
>
_priv == NULL == Oops.


I think my version of the patch is better.

Ohh and would you mind submitting patches inline? Makes it a lot easier to
quote and comment.


--
Jesper


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