KEYS: ensure we free the assoc array edit if edit is valid

__key_link_end is not freeing the associated array edit structure
and this leads to a 512 byte memory leak each time an identical
existing key is added with add_key().

The reason the add_key() system call returns okay is that
key_create_or_update() calls __key_link_begin() before checking to see
whether it can update a key directly rather than adding/replacing - which
it turns out it can.  Thus __key_link() is not called through
__key_instantiate_and_link() and __key_link_end() must cancel the edit.

CVE-2015-1333

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index e72548b5897ec237dd7463374871538c81a84fd7..d33437007ad229313a5ef483826e427a74350876 100644 (file)
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1181,9 +1181,11 @@ void __key_link_end(struct key *keyring,
        if (index_key->type == &key_type_keyring)
                up_write(&keyring_serialise_link_sem);
 
-       if (edit && !edit->dead_leaf) {
-               key_payload_reserve(keyring,
-                                   keyring->datalen - KEYQUOTA_LINK_BYTES);
+       if (edit) {
+               if (!edit->dead_leaf) {
+                       key_payload_reserve(keyring,
+                               keyring->datalen - KEYQUOTA_LINK_BYTES);
+               }
                assoc_array_cancel_edit(edit);
        }
        up_write(&keyring->sem);