ensure ibf_load_setup is only passed String params

In cases where RubyVM::InstructionSequence.load_from_binary() is
passed a param other than a String, we attempt to call the
RSTRING_LENINT macro on it which can cause a segfault.

ex:
```
var_0 = 0
RubyVM::InstructionSequence.load_from_binary(var_0)
```

This commit adds a type check to raise unless we are provided
a String.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/ruby/test_iseq.rb b/test/ruby/test_iseq.rb
index dbf91fe8c9..d2a39e673f 100644
--- a/test/ruby/test_iseq.rb
+++ b/test/ruby/test_iseq.rb
@@ -850,4 +850,11 @@ class TestISeq < Test::Unit::TestCase
       RubyVM::InstructionSequence.compile_prism(Object.new)
     end
   end
+
+  def test_load_from_binary_only_accepts_string_param
+    assert_raise(TypeError) do
+      var_0 = 0
+      RubyVM::InstructionSequence.load_from_binary(var_0)
+    end
+  end
 end