Merge branch 'keys-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull key handling fixes from David Howells:
 "Here are two patches, the first of which at least should go upstream
  immediately:

  (1) Prevent a user-triggerable crash in the keyrings destructor when a
      negatively instantiated keyring is garbage collected.  I have also
      seen this triggered for user type keys.

  (2) Prevent the user from using requesting that a keyring be created
      and instantiated through an upcall.  Doing so is probably safe
      since the keyring type ignores the arguments to its instantiation
      function - but we probably shouldn't let keyrings be created in
      this manner"

* 'keys-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  KEYS: Don't permit request_key() to construct a new keyring
  KEYS: Fix crash when attempt to garbage collect an uninstantiated keyring

security/keys/gc.c

@@ -134,8 +134,10 @@ static noinline void key_gc_unused_keys(struct list_head *keys)
 		kdebug("- %u", key->serial);
 		key_check(key);
 
-		/* Throw away the key data */
-		if (key->type->destroy)
+		/* Throw away the key data if the key is instantiated */
+		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
+		    !test_bit(KEY_FLAG_NEGATIVE, &key->flags) &&
+		    key->type->destroy)
 			key->type->destroy(key);
 
 		security_key_free(key);

security/keys/request_key.c

@@ -440,6 +440,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
 
 	kenter("");
 
+	if (ctx->index_key.type == &key_type_keyring)
+		return ERR_PTR(-EPERM);
+	
 	user = key_user_lookup(current_fsuid());
 	if (!user)
 		return ERR_PTR(-ENOMEM);