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, 5 insertions, 5 deletions

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index c8c47fc72653..001bcb0f2480 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -441,7 +441,7 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
 	/* Allocate per-cpu TFM entry pointer */
 	tmp->tfm_entry = alloc_percpu(struct tipc_tfm *);
 	if (!tmp->tfm_entry) {
-		kzfree(tmp);
+		kfree_sensitive(tmp);
 		return -ENOMEM;
 	}
 
@@ -491,7 +491,7 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
 	/* Not any TFM is allocated? */
 	if (!tfm_cnt) {
 		free_percpu(tmp->tfm_entry);
-		kzfree(tmp);
+		kfree_sensitive(tmp);
 		return err;
 	}
 
@@ -545,7 +545,7 @@ static int tipc_aead_clone(struct tipc_aead **dst, struct tipc_aead *src)
 
 	aead->tfm_entry = alloc_percpu_gfp(struct tipc_tfm *, GFP_ATOMIC);
 	if (unlikely(!aead->tfm_entry)) {
-		kzfree(aead);
+		kfree_sensitive(aead);
 		return -ENOMEM;
 	}
 
@@ -1352,7 +1352,7 @@ int tipc_crypto_start(struct tipc_crypto **crypto, struct net *net,
 	/* Allocate statistic structure */
 	c->stats = alloc_percpu_gfp(struct tipc_crypto_stats, GFP_ATOMIC);
 	if (!c->stats) {
-		kzfree(c);
+		kfree_sensitive(c);
 		return -ENOMEM;
 	}
 
@@ -1408,7 +1408,7 @@ void tipc_crypto_stop(struct tipc_crypto **crypto)
 	free_percpu(c->stats);
 
 	*crypto = NULL;
-	kzfree(c);
+	kfree_sensitive(c);
 }
 
 void tipc_crypto_timeout(struct tipc_crypto *rx)