crypto: fix zero byte allocation assertion failure

When an empty string was passed, malloc might have returned a nullptr
depending on the platform, causing an assertion failure. This change
makes private key parsing behave as public key parsing does, causing
a BIO error instead that can be caught in JS.

Fixes: #25247

PR-URL: #25248
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

src/node_crypto.cc

@@ -2696,7 +2696,7 @@ static bool IsSupportedAuthenticatedMode(const EVP_CIPHER_CTX* ctx) {
 template <typename T>
 static T* MallocOpenSSL(size_t count) {
   void* mem = OPENSSL_malloc(MultiplyWithOverflowCheck(count, sizeof(T)));
-  CHECK_NOT_NULL(mem);
+  CHECK_IMPLIES(mem == nullptr, count == 0);
   return static_cast<T*>(mem);
 }
 
@@ -2854,7 +2854,8 @@ static EVPKeyPointer ParsePrivateKey(const PrivateKeyEncodingConfig& config,
 
   if (config.format_ == kKeyFormatPEM) {
     BIOPointer bio(BIO_new_mem_buf(key, key_len));
-    CHECK(bio);
+    if (!bio)
+      return pkey;
 
     char* pass = const_cast<char*>(config.passphrase_.get());
     pkey.reset(PEM_read_bio_PrivateKey(bio.get(),
@@ -2869,7 +2870,8 @@ static EVPKeyPointer ParsePrivateKey(const PrivateKeyEncodingConfig& config,
       pkey.reset(d2i_PrivateKey(EVP_PKEY_RSA, nullptr, &p, key_len));
     } else if (config.type_.ToChecked() == kKeyEncodingPKCS8) {
       BIOPointer bio(BIO_new_mem_buf(key, key_len));
-      CHECK(bio);
+      if (!bio)
+        return pkey;
       char* pass = const_cast<char*>(config.passphrase_.get());
       pkey.reset(d2i_PKCS8PrivateKey_bio(bio.get(),
                                          nullptr,

test/parallel/test-crypto-key-objects.js

@@ -105,3 +105,10 @@ const privatePem = fixtures.readSync('test_rsa_privkey.pem', 'ascii');
     }
   }
 }
+
+{
+  // This should not cause a crash: https://github.com/nodejs/node/issues/25247
+  assert.throws(() => {
+    createPrivateKey({ key: '' });
+  }, /null/);
+}