KEYS: encrypted: fix buffer overread in valid_master_desc()

[sagit-ice-cold/kernel_xiaomi_msm8998.git] / security / keys / encrypted-keys / encrypted.c

diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
index ce295c0..e44e844 100644 (file)
--- a/security/keys/encrypted-keys/encrypted.c
+++ b/security/keys/encrypted-keys/encrypted.c
@@ -141,23 +141,22 @@ static int valid_ecryptfs_desc(const char *ecryptfs_desc)
  */
 static int valid_master_desc(const char *new_desc, const char *orig_desc)
 {
-       if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
-               if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
-                       goto out;
-               if (orig_desc)
-                       if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
-                               goto out;
-       } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
-               if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
-                       goto out;
-               if (orig_desc)
-                       if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
-                               goto out;
-       } else
-               goto out;
+       int prefix_len;
+
+       if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
+               prefix_len = KEY_TRUSTED_PREFIX_LEN;
+       else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
+               prefix_len = KEY_USER_PREFIX_LEN;
+       else
+               return -EINVAL;
+
+       if (!new_desc[prefix_len])
+               return -EINVAL;
+
+       if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
+               return -EINVAL;
+
        return 0;
-out:
-       return -EINVAL;
 }
 
 /*