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, 12 insertions, 12 deletions

diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c
index af4f50fda9e3..4c010c9a6af1 100644
--- a/security/apparmor/policy.c
+++ b/security/apparmor/policy.c
@@ -187,9 +187,9 @@ static void aa_free_data(void *ptr, void *arg)
 {
 	struct aa_data *data = ptr;
 
-	kzfree(data->data);
-	kzfree(data->key);
-	kzfree(data);
+	kfree_sensitive(data->data);
+	kfree_sensitive(data->key);
+	kfree_sensitive(data);
 }
 
 /**
@@ -217,19 +217,19 @@ void aa_free_profile(struct aa_profile *profile)
 	aa_put_profile(rcu_access_pointer(profile->parent));
 
 	aa_put_ns(profile->ns);
-	kzfree(profile->rename);
+	kfree_sensitive(profile->rename);
 
 	aa_free_file_rules(&profile->file);
 	aa_free_cap_rules(&profile->caps);
 	aa_free_rlimit_rules(&profile->rlimits);
 
 	for (i = 0; i < profile->xattr_count; i++)
-		kzfree(profile->xattrs[i]);
-	kzfree(profile->xattrs);
+		kfree_sensitive(profile->xattrs[i]);
+	kfree_sensitive(profile->xattrs);
 	for (i = 0; i < profile->secmark_count; i++)
-		kzfree(profile->secmark[i].label);
-	kzfree(profile->secmark);
-	kzfree(profile->dirname);
+		kfree_sensitive(profile->secmark[i].label);
+	kfree_sensitive(profile->secmark);
+	kfree_sensitive(profile->dirname);
 	aa_put_dfa(profile->xmatch);
 	aa_put_dfa(profile->policy.dfa);
 
@@ -237,14 +237,14 @@ void aa_free_profile(struct aa_profile *profile)
 		rht = profile->data;
 		profile->data = NULL;
 		rhashtable_free_and_destroy(rht, aa_free_data, NULL);
-		kzfree(rht);
+		kfree_sensitive(rht);
 	}
 
-	kzfree(profile->hash);
+	kfree_sensitive(profile->hash);
 	aa_put_loaddata(profile->rawdata);
 	aa_label_destroy(&profile->label);
 
-	kzfree(profile);
+	kfree_sensitive(profile);
 }
 
 /**