Add length check for CExtKey deserialization

Github-Pull: #11081
Rebased-From: 07685d1bc1
Tree-SHA512: 7f6b9ca6714d059d500531eb842c1c25edfa04ecba0ea1d9a28010fced657c066cea67d2016bbaa9b96c431a05ca9c0dcf2ba301898ecf96a65a4e01aac7fae9

src/key.h

@@ -172,6 +172,8 @@ struct CExtKey {
     {
         unsigned int len = ::ReadCompactSize(s);
         unsigned char code[BIP32_EXTKEY_SIZE];
+        if (len != BIP32_EXTKEY_SIZE)
+            throw std::runtime_error("Invalid extended key size\n");
         s.read((char *)&code[0], len);
         Decode(code);
     }