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, 7 insertions, 7 deletions

diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index b67322abcc33..dc345ac93205 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -163,10 +163,10 @@ static void do_loaddata_free(struct work_struct *work)
 		aa_put_ns(ns);
 	}
 
-	kzfree(d->hash);
-	kzfree(d->name);
+	kfree_sensitive(d->hash);
+	kfree_sensitive(d->name);
 	kvfree(d->data);
-	kzfree(d);
+	kfree_sensitive(d);
 }
 
 void aa_loaddata_kref(struct kref *kref)
@@ -894,7 +894,7 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 		while (unpack_strdup(e, &key, NULL)) {
 			data = kzalloc(sizeof(*data), GFP_KERNEL);
 			if (!data) {
-				kzfree(key);
+				kfree_sensitive(key);
 				goto fail;
 			}
 
@@ -902,8 +902,8 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
 			data->size = unpack_blob(e, &data->data, NULL);
 			data->data = kvmemdup(data->data, data->size);
 			if (data->size && !data->data) {
-				kzfree(data->key);
-				kzfree(data);
+				kfree_sensitive(data->key);
+				kfree_sensitive(data);
 				goto fail;
 			}
 
@@ -1037,7 +1037,7 @@ void aa_load_ent_free(struct aa_load_ent *ent)
 		aa_put_profile(ent->old);
 		aa_put_profile(ent->new);
 		kfree(ent->ns_name);
-		kzfree(ent);
+		kfree_sensitive(ent);
 	}
 }