src: Malloc/Calloc size 0 returns non-null pointer

Change `Malloc()/Calloc()` so that size zero does not return a null
pointer, consistent with prior behavior.

Fixes: https://github.com/nodejs/node/issues/8571
PR-URL: https://github.com/nodejs/node/pull/8572
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@keybase.io>
Reviewed-By: Yorkie Liu <yorkiefixer@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

src/util-inl.h

@@ -234,11 +234,13 @@ void* Realloc(void* pointer, size_t size) {
 
 // As per spec realloc behaves like malloc if passed nullptr.
 void* Malloc(size_t size) {
+  if (size == 0) size = 1;
   return Realloc(nullptr, size);
 }
 
 void* Calloc(size_t n, size_t size) {
-  if ((n == 0) || (size == 0)) return nullptr;
+  if (n == 0) n = 1;
+  if (size == 0) size = 1;
   CHECK_GE(n * size, n);  // Overflow guard.
   return calloc(n, size);
 }

test/cctest/util.cc

@@ -74,3 +74,17 @@ TEST(UtilTest, ToLower) {
   EXPECT_EQ('a', ToLower('a'));
   EXPECT_EQ('a', ToLower('A'));
 }
+
+TEST(UtilTest, Malloc) {
+  using node::Malloc;
+  EXPECT_NE(nullptr, Malloc(0));
+  EXPECT_NE(nullptr, Malloc(1));
+}
+
+TEST(UtilTest, Calloc) {
+  using node::Calloc;
+  EXPECT_NE(nullptr, Calloc(0, 0));
+  EXPECT_NE(nullptr, Calloc(1, 0));
+  EXPECT_NE(nullptr, Calloc(0, 1));
+  EXPECT_NE(nullptr, Calloc(1, 1));
+}

test/parallel/test-crypto-pbkdf2.js

@@ -79,3 +79,11 @@ assert.throws(function() {
 assert.throws(function() {
   crypto.pbkdf2('password', 'salt', 1, -1, common.fail);
 }, /Bad key length/);
+
+// Should not get FATAL ERROR with empty password and salt
+// https://github.com/nodejs/node/issues/8571
+assert.doesNotThrow(() => {
+  crypto.pbkdf2('', '', 1, 32, 'sha256', common.mustCall((e) => {
+    assert.ifError(e);
+  }));
+});