From a5b809e994ce10d265e73f8c9d7c042e5e84d171 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Fri, 23 Aug 2019 13:00:17 +0900
Subject: Check metadata a bit more

---
 ext/digest/digest.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/ext/digest/digest.c b/ext/digest/digest.c
index 73655c5bb5..a59f880ac7 100644
--- a/ext/digest/digest.c
+++ b/ext/digest/digest.c
@@ -554,10 +554,22 @@ get_digest_base_metadata(VALUE klass)
     if (NIL_P(p))
         rb_raise(rb_eRuntimeError, "Digest::Base cannot be directly inherited in Ruby");
 
+    if (!RB_TYPE_P(obj, T_DATA) || RTYPEDDATA_P(obj)) {
+      wrong:
+        if (p == klass)
+            rb_raise(rb_eTypeError, "%"PRIsVALUE"::metadata is not initialized properly",
+                     klass);
+        else
+            rb_raise(rb_eTypeError, "%"PRIsVALUE"(%"PRIsVALUE")::metadata is not initialized properly",
+                     klass, p);
+    }
+
 #undef RUBY_UNTYPED_DATA_WARNING
 #define RUBY_UNTYPED_DATA_WARNING 0
     Data_Get_Struct(obj, rb_digest_metadata_t, algo);
 
+    if (!algo) goto wrong;
+
     switch (algo->api_version) {
       case 3:
         break;
-- 
cgit v1.2.3