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/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 814e23d3ce7c..c04fc6cf6583 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -9836,7 +9836,7 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 
 		if ((ibss.chandef.width != NL80211_CHAN_WIDTH_20_NOHT) &&
 		    no_ht) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return -EINVAL;
 		}
 	}
@@ -9848,7 +9848,7 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 		int r = validate_pae_over_nl80211(rdev, info);
 
 		if (r < 0) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return r;
 		}
 
@@ -9861,7 +9861,7 @@ static int nl80211_join_ibss(struct sk_buff *skb, struct genl_info *info)
 	wdev_lock(dev->ieee80211_ptr);
 	err = __cfg80211_join_ibss(rdev, dev, &ibss, connkeys);
 	if (err)
-		kzfree(connkeys);
+		kfree_sensitive(connkeys);
 	else if (info->attrs[NL80211_ATTR_SOCKET_OWNER])
 		dev->ieee80211_ptr->conn_owner_nlportid = info->snd_portid;
 	wdev_unlock(dev->ieee80211_ptr);
@@ -10289,7 +10289,7 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 
 	if (info->attrs[NL80211_ATTR_HT_CAPABILITY]) {
 		if (!info->attrs[NL80211_ATTR_HT_CAPABILITY_MASK]) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return -EINVAL;
 		}
 		memcpy(&connect.ht_capa,
@@ -10307,7 +10307,7 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 
 	if (info->attrs[NL80211_ATTR_VHT_CAPABILITY]) {
 		if (!info->attrs[NL80211_ATTR_VHT_CAPABILITY_MASK]) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return -EINVAL;
 		}
 		memcpy(&connect.vht_capa,
@@ -10321,7 +10321,7 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 		       (rdev->wiphy.features & NL80211_FEATURE_QUIET)) &&
 		    !wiphy_ext_feature_isset(&rdev->wiphy,
 					     NL80211_EXT_FEATURE_RRM)) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return -EINVAL;
 		}
 		connect.flags |= ASSOC_REQ_USE_RRM;
@@ -10329,21 +10329,21 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 
 	connect.pbss = nla_get_flag(info->attrs[NL80211_ATTR_PBSS]);
 	if (connect.pbss && !rdev->wiphy.bands[NL80211_BAND_60GHZ]) {
-		kzfree(connkeys);
+		kfree_sensitive(connkeys);
 		return -EOPNOTSUPP;
 	}
 
 	if (info->attrs[NL80211_ATTR_BSS_SELECT]) {
 		/* bss selection makes no sense if bssid is set */
 		if (connect.bssid) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return -EINVAL;
 		}
 
 		err = parse_bss_select(info->attrs[NL80211_ATTR_BSS_SELECT],
 				       wiphy, &connect.bss_select);
 		if (err) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			return err;
 		}
 	}
@@ -10373,13 +10373,13 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 		   info->attrs[NL80211_ATTR_FILS_ERP_REALM] ||
 		   info->attrs[NL80211_ATTR_FILS_ERP_NEXT_SEQ_NUM] ||
 		   info->attrs[NL80211_ATTR_FILS_ERP_RRK]) {
-		kzfree(connkeys);
+		kfree_sensitive(connkeys);
 		return -EINVAL;
 	}
 
 	if (nla_get_flag(info->attrs[NL80211_ATTR_EXTERNAL_AUTH_SUPPORT])) {
 		if (!info->attrs[NL80211_ATTR_SOCKET_OWNER]) {
-			kzfree(connkeys);
+			kfree_sensitive(connkeys);
 			GENL_SET_ERR_MSG(info,
 					 "external auth requires connection ownership");
 			return -EINVAL;
@@ -10392,7 +10392,7 @@ static int nl80211_connect(struct sk_buff *skb, struct genl_info *info)
 	err = cfg80211_connect(rdev, dev, &connect, connkeys,
 			       connect.prev_bssid);
 	if (err)
-		kzfree(connkeys);
+		kfree_sensitive(connkeys);
 
 	if (!err && info->attrs[NL80211_ATTR_SOCKET_OWNER]) {
 		dev->ieee80211_ptr->conn_owner_nlportid = info->snd_portid;