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, 14 insertions, 14 deletions

diff --git a/drivers/crypto/caam/caampkc.c b/drivers/crypto/caam/caampkc.c
index 2e44d685618f..dd5f101e43f8 100644
--- a/drivers/crypto/caam/caampkc.c
+++ b/drivers/crypto/caam/caampkc.c
@@ -854,14 +854,14 @@ static int caam_rsa_dec(struct akcipher_request *req)
 
 static void caam_rsa_free_key(struct caam_rsa_key *key)
 {
-	kzfree(key->d);
-	kzfree(key->p);
-	kzfree(key->q);
-	kzfree(key->dp);
-	kzfree(key->dq);
-	kzfree(key->qinv);
-	kzfree(key->tmp1);
-	kzfree(key->tmp2);
+	kfree_sensitive(key->d);
+	kfree_sensitive(key->p);
+	kfree_sensitive(key->q);
+	kfree_sensitive(key->dp);
+	kfree_sensitive(key->dq);
+	kfree_sensitive(key->qinv);
+	kfree_sensitive(key->tmp1);
+	kfree_sensitive(key->tmp2);
 	kfree(key->e);
 	kfree(key->n);
 	memset(key, 0, sizeof(*key));
@@ -1018,17 +1018,17 @@ static void caam_rsa_set_priv_key_form(struct caam_rsa_ctx *ctx,
 	return;
 
 free_dq:
-	kzfree(rsa_key->dq);
+	kfree_sensitive(rsa_key->dq);
 free_dp:
-	kzfree(rsa_key->dp);
+	kfree_sensitive(rsa_key->dp);
 free_tmp2:
-	kzfree(rsa_key->tmp2);
+	kfree_sensitive(rsa_key->tmp2);
 free_tmp1:
-	kzfree(rsa_key->tmp1);
+	kfree_sensitive(rsa_key->tmp1);
 free_q:
-	kzfree(rsa_key->q);
+	kfree_sensitive(rsa_key->q);
 free_p:
-	kzfree(rsa_key->p);
+	kfree_sensitive(rsa_key->p);
 }
 
 static int caam_rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,