src: add Malloc() size param + overflow detection

Adds an optional second parameter to `node::Malloc()` and
an optional third parameter to `node::Realloc()` giving the
size/number of items to be allocated, in the style of `calloc(3)`.

Use a proper overflow check using division;
the previous `CHECK_GE(n * size, n);` would not detect all cases
of overflow (e.g. `size == SIZE_MAX / 2 && n == 3`).

PR-URL: https://github.com/nodejs/node/pull/8482
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/string_bytes.cc b/src/string_bytes.cc
index fa641af746..fddf61de63 100644
--- a/src/string_bytes.cc
+++ b/src/string_bytes.cc
@@ -54,7 +54,7 @@ class ExternString: public ResourceType {
       return scope.Escape(String::Empty(isolate));
 
     TypeName* new_data =
-        static_cast<TypeName*>(node::Malloc(length * sizeof(*new_data)));
+        static_cast<TypeName*>(node::Malloc(length, sizeof(*new_data)));
     if (new_data == nullptr) {
       return Local<String>();
     }