crypto: add more keylen sanity checks in pbkdf2

issue #2987 makes the point that crypto.pbkdf2 should not fail silently
and accept invalid but numeric values like NaN and Infinity. We already
check if the keylen is lower than 0, so extending that to NaN and
Infinity should make sense.

Fixes: #2987

PR-URL: #3029
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

src/node_crypto.cc

@@ -19,6 +19,7 @@
 #include "CNNICHashWhitelist.inc"
 
 #include <errno.h>
+#include <math.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -4760,7 +4761,7 @@ void PBKDF2(const FunctionCallbackInfo<Value>& args) {
   char* salt = nullptr;
   ssize_t passlen = -1;
   ssize_t saltlen = -1;
-  ssize_t keylen = -1;
+  double keylen = -1;
   ssize_t iter = -1;
   PBKDF2Request* req = nullptr;
   Local<Object> obj;
@@ -4813,8 +4814,8 @@ void PBKDF2(const FunctionCallbackInfo<Value>& args) {
     goto err;
   }
 
-  keylen = args[3]->Int32Value();
-  if (keylen < 0) {
+  keylen = args[3]->NumberValue();
+  if (keylen < 0 || isnan(keylen) || isinf(keylen)) {
     type_error = "Bad key length";
     goto err;
   }
@@ -4841,7 +4842,7 @@ void PBKDF2(const FunctionCallbackInfo<Value>& args) {
                           saltlen,
                           salt,
                           iter,
-                          keylen);
+                          static_cast<ssize_t>(keylen));
 
   if (args[5]->IsFunction()) {
     obj->Set(env->ondone_string(), args[5]);

test/parallel/test-crypto-pbkdf2.js

@@ -59,3 +59,31 @@ function ondone(err, key) {
 assert.throws(function() {
   crypto.pbkdf2('password', 'salt', 1, 20, null);
 });
+
+// Should not work with Infinity key length
+assert.throws(function() {
+  crypto.pbkdf2('password', 'salt', 1, Infinity, assert.fail);
+}, function(err) {
+  return err instanceof Error && err.message === 'Bad key length';
+});
+
+// Should not work with negative Infinity key length
+assert.throws(function() {
+  crypto.pbkdf2('password', 'salt', 1, -Infinity, assert.fail);
+}, function(err) {
+  return err instanceof Error && err.message === 'Bad key length';
+});
+
+// Should not work with NaN key length
+assert.throws(function() {
+  crypto.pbkdf2('password', 'salt', 1, NaN, assert.fail);
+}, function(err) {
+  return err instanceof Error && err.message === 'Bad key length';
+});
+
+// Should not work with negative key length
+assert.throws(function() {
+  crypto.pbkdf2('password', 'salt', 1, -1, assert.fail);
+}, function(err) {
+  return err instanceof Error && err.message === 'Bad key length';
+});