crypto: fix rsa key gen with non-default exponent

EVP_PKEY_CTX_set_rsa_keygen_pubexp() accepts ownership of the exponent
on success, so do not free it.

Fixes: #27087
Fixes: #29433

PR-URL: #27092
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/node_crypto.cc

@@ -4864,8 +4864,10 @@ class RSAKeyPairGenerationConfig : public KeyPairGenerationConfig {
       BignumPointer bn(BN_new());
       CHECK_NOT_NULL(bn.get());
       CHECK(BN_set_word(bn.get(), exponent_));
+      // EVP_CTX acceps ownership of bn on success.
       if (EVP_PKEY_CTX_set_rsa_keygen_pubexp(ctx.get(), bn.get()) <= 0)
         return false;
+      bn.release();
     }
 
     return true;

test/parallel/test-crypto-keygen.js

@@ -86,7 +86,7 @@ function convertDERToPEM(label, der) {
   // To make the test faster, we will only test sync key generation once and
   // with a relatively small key.
   const ret = generateKeyPairSync('rsa', {
-    publicExponent: 0x10001,
+    publicExponent: 3,
     modulusLength: 512,
     publicKeyEncoding: {
       type: 'pkcs1',
@@ -144,7 +144,7 @@ function convertDERToPEM(label, der) {
 
   // Now do the same with an encrypted private key.
   generateKeyPair('rsa', {
-    publicExponent: 0x10001,
+    publicExponent: 0x1001,
     modulusLength: 512,
     publicKeyEncoding: {
       type: 'pkcs1',