crypto: throw on SignFinal failure

fix #6963

src/node_crypto.cc

@@ -3005,9 +3005,15 @@ class Sign : public ObjectWrap {
     if(!BIO_write(bp, key_pem, key_pemLen)) return 0;
 
     pkey = PEM_read_bio_PrivateKey( bp, NULL, NULL, NULL );
-    if (pkey == NULL) return 0;
+    if (pkey == NULL) {
+      ERR_print_errors_fp(stderr);
+      return 0;
+    }
 
-    EVP_SignFinal(&mdctx, *md_value, md_len, pkey);
+    if (!EVP_SignFinal(&mdctx, *md_value, md_len, pkey)) {
+      ERR_print_errors_fp(stderr);
+      return 0;
+    }
     EVP_MD_CTX_cleanup(&mdctx);
     initialised_ = false;
     EVP_PKEY_free(pkey);
@@ -3107,8 +3113,11 @@ class Sign : public ObjectWrap {
 
     int r = sign->SignFinal(&md_value, &md_len, buf, len);
     if (r == 0) {
+      delete [] buf;
+      delete [] md_value;
       md_value = NULL;
       md_len = r;
+      return ThrowException(Exception::Error(String::New("SignFinal error")));
     }
 
     delete [] buf;

test/simple/test-crypto.js

@@ -937,3 +937,16 @@ assert.throws(function() {
 assert.throws(function() {
   crypto.createVerify('RSA-SHA1').update('0', 'hex');
 }, /Bad input string/);
+
+assert.throws(function() {
+  var private = [
+    '-----BEGIN RSA PRIVATE KEY-----',
+    'MIGrAgEAAiEA+3z+1QNF2/unumadiwEr+C5vfhezsb3hp4jAnCNRpPcCAwEAAQIgQNriSQK4',
+    'EFwczDhMZp2dvbcz7OUUyt36z3S4usFPHSECEQD/41K7SujrstBfoCPzwC1xAhEA+5kt4BJy',
+    'eKN7LggbF3Dk5wIQN6SL+fQ5H/+7NgARsVBp0QIRANxYRukavs4QvuyNhMx+vrkCEQCbf6j/',
+    'Ig6/HueCK/0Jkmp+',
+    '-----END RSA PRIVATE KEY-----',
+    ''
+  ].join('\n');
+  crypto.createSign('RSA-SHA256').update('test').sign(private);
+}, /SignFinal/);