Tighten behavior of _rs_allocate on Windows.

For Windows, we are simply using calloc, which has two annoyances:
the memory has more permissions than needed by default, and it comes
from the process heap, which looks like a memory leak since this memory
is rightfully never freed.

This switches _rs_alloc on Windows to use VirtualAlloc, which restricts the
memory to READ|WRITE and keeps the memory out of the process heap.

ok deraadt@

2 files changed, 14 insertions, 8 deletions

diff --git a/src/lib/libcrypto/arc4random/arc4random_win.h b/src/lib/libcrypto/arc4random/arc4random_win.h
index 48a1bda128..deec8a1efe 100644
--- a/src/lib/libcrypto/arc4random/arc4random_win.h
+++ b/src/lib/libcrypto/arc4random/arc4random_win.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random_win.h,v 1.5 2015/01/15 06:57:18 deraadt Exp $      */
+/*      $OpenBSD: arc4random_win.h,v 1.6 2016/06/30 12:17:29 bcook Exp $        */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -52,13 +52,16 @@ _getentropy_fail(void)
 static inline int
 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
 {
-        *rsp = calloc(1, sizeof(**rsp));
+        *rsp = VirtualAlloc(NULL, sizeof(**rsp),
+            MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
         if (*rsp == NULL)
                 return (-1);
 
-        *rsxp = calloc(1, sizeof(**rsxp));
+        *rsxp = VirtualAlloc(NULL, sizeof(**rsxp),
+            MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
         if (*rsxp == NULL) {
-                free(*rsp);
+                VirtualFree(*rsp, 0, MEM_RELEASE);
+                *rsp = NULL;
                 return (-1);
         }
         return (0);
diff --git a/src/lib/libcrypto/crypto/arc4random_win.h b/src/lib/libcrypto/crypto/arc4random_win.h
index 48a1bda128..deec8a1efe 100644
--- a/src/lib/libcrypto/crypto/arc4random_win.h
+++ b/src/lib/libcrypto/crypto/arc4random_win.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random_win.h,v 1.5 2015/01/15 06:57:18 deraadt Exp $      */
+/*      $OpenBSD: arc4random_win.h,v 1.6 2016/06/30 12:17:29 bcook Exp $        */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -52,13 +52,16 @@ _getentropy_fail(void)
 static inline int
 _rs_allocate(struct _rs **rsp, struct _rsx **rsxp)
 {
-        *rsp = calloc(1, sizeof(**rsp));
+        *rsp = VirtualAlloc(NULL, sizeof(**rsp),
+            MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
         if (*rsp == NULL)
                 return (-1);
 
-        *rsxp = calloc(1, sizeof(**rsxp));
+        *rsxp = VirtualAlloc(NULL, sizeof(**rsxp),
+            MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);
         if (*rsxp == NULL) {
-                free(*rsp);
+                VirtualFree(*rsp, 0, MEM_RELEASE);
+                *rsp = NULL;
                 return (-1);
         }
         return (0);