os,vm: fix segfaults and CHECK failure

Fixes multiple possible segmentation faults in node_contextify.cc and
an assertion failure in node_os.cc

Fixes: https://github.com/nodejs/node/issues/12369
Fixes: https://github.com/nodejs/node/issues/12370
PR-URL: https://github.com/nodejs/node/pull/12371
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/node_os.cc b/src/node_os.cc
index d7be9095b1..fad1946953 100644
--- a/src/node_os.cc
+++ b/src/node_os.cc
@@ -57,6 +57,7 @@ using v8::Function;
 using v8::FunctionCallbackInfo;
 using v8::Integer;
 using v8::Local;
+using v8::MaybeLocal;
 using v8::Null;
 using v8::Number;
 using v8::Object;
@@ -339,7 +340,12 @@ static void GetUserInfo(const FunctionCallbackInfo<Value>& args) {
 
   if (args[0]->IsObject()) {
     Local<Object> options = args[0].As<Object>();
-    Local<Value> encoding_opt = options->Get(env->encoding_string());
+    MaybeLocal<Value> maybe_encoding = options->Get(env->context(),
+                                                    env->encoding_string());
+    if (maybe_encoding.IsEmpty())
+      return;
+
+    Local<Value> encoding_opt = maybe_encoding.ToLocalChecked();
     encoding = ParseEncoding(env->isolate(), encoding_opt, UTF8);
   } else {
     encoding = UTF8;