mm, treewide: rename kzfree() to kfree_sensitive()

As said by Linus:

  A symmetric naming is only helpful if it implies symmetries in use.
  Otherwise it's actively misleading.

  In "kzalloc()", the z is meaningful and an important part of what the
  caller wants.

  In "kzfree()", the z is actively detrimental, because maybe in the
  future we really _might_ want to use that "memfill(0xdeadbeef)" or
  something. The "zero" part of the interface isn't even _relevant_.

The main reason that kzfree() exists is to clear sensitive information
that should not be leaked to other future users of the same memory
objects.

Rename kzfree() to kfree_sensitive() to follow the example of the recently
added kvfree_sensitive() and make the intention of the API more explicit.
In addition, memzero_explicit() is used to clear the memory to make sure
that it won't get optimized away by the compiler.

The renaming is done by using the command sequence:

  git grep -w --name-only kzfree |\
  xargs sed -i 's/kzfree/kfree_sensitive/'

followed by some editing of the kfree_sensitive() kerneldoc and adding
a kzfree backward compatibility macro in slab.h.

[akpm@linux-foundation.org: fs/crypto/inline_crypt.c needs linux/slab.h]
[akpm@linux-foundation.org: fix fs/crypto/inline_crypt.c some more]

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Howells <dhowells@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Joe Perches <joe@perches.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Jason A . Donenfeld" <Jason@zx2c4.com>
Link: http://lkml.kernel.org/r/20200616154311.12314-3-longman@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/net/mac802154/llsec.c b/net/mac802154/llsec.c
index c079ee69d3d0..585d33144c33 100644
--- a/net/mac802154/llsec.c
+++ b/net/mac802154/llsec.c
@@ -49,7 +49,7 @@ void mac802154_llsec_destroy(struct mac802154_llsec *sec)
 
 		msl = container_of(sl, struct mac802154_llsec_seclevel, level);
 		list_del(&sl->list);
-		kzfree(msl);
+		kfree_sensitive(msl);
 	}
 
 	list_for_each_entry_safe(dev, dn, &sec->table.devices, list) {
@@ -66,7 +66,7 @@ void mac802154_llsec_destroy(struct mac802154_llsec *sec)
 		mkey = container_of(key->key, struct mac802154_llsec_key, key);
 		list_del(&key->list);
 		llsec_key_put(mkey);
-		kzfree(key);
+		kfree_sensitive(key);
 	}
 }
 
@@ -155,7 +155,7 @@ err_tfm:
 		if (key->tfm[i])
 			crypto_free_aead(key->tfm[i]);
 
-	kzfree(key);
+	kfree_sensitive(key);
 	return NULL;
 }
 
@@ -170,7 +170,7 @@ static void llsec_key_release(struct kref *ref)
 		crypto_free_aead(key->tfm[i]);
 
 	crypto_free_sync_skcipher(key->tfm0);
-	kzfree(key);
+	kfree_sensitive(key);
 }
 
 static struct mac802154_llsec_key*
@@ -261,7 +261,7 @@ int mac802154_llsec_key_add(struct mac802154_llsec *sec,
 	return 0;
 
 fail:
-	kzfree(new);
+	kfree_sensitive(new);
 	return -ENOMEM;
 }
 
@@ -341,10 +341,10 @@ static void llsec_dev_free(struct mac802154_llsec_device *dev)
 				      devkey);
 
 		list_del(&pos->list);
-		kzfree(devkey);
+		kfree_sensitive(devkey);
 	}
 
-	kzfree(dev);
+	kfree_sensitive(dev);
 }
 
 int mac802154_llsec_dev_add(struct mac802154_llsec *sec,
@@ -682,7 +682,7 @@ llsec_do_encrypt_auth(struct sk_buff *skb, const struct mac802154_llsec *sec,
 
 	rc = crypto_aead_encrypt(req);
 
-	kzfree(req);
+	kfree_sensitive(req);
 
 	return rc;
 }
@@ -886,7 +886,7 @@ llsec_do_decrypt_auth(struct sk_buff *skb, const struct mac802154_llsec *sec,
 
 	rc = crypto_aead_decrypt(req);
 
-	kzfree(req);
+	kfree_sensitive(req);
 	skb_trim(skb, skb->len - authlen);
 
 	return rc;
@@ -926,7 +926,7 @@ llsec_update_devkey_record(struct mac802154_llsec_device *dev,
 		if (!devkey)
 			list_add_rcu(&next->devkey.list, &dev->dev.keys);
 		else
-			kzfree(next);
+			kfree_sensitive(next);
 
 		spin_unlock_bh(&dev->lock);
 	}