From 3ca29d6f501ba5d2608b99e6afa471e1e91001e8 Mon Sep 17 00:00:00 2001
From: Matthew Parkinson <mattpark@microsoft.com>
Date: Mon, 9 Nov 2020 21:17:59 +0000
Subject: [PATCH] Make POSIX COMMIT CHECKS  mode fill memory

This simulates the pages being switched off with unexpected content, and
thus, when turned on we don't assume they have been unchanged.
---
 src/pal/pal_posix.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/pal/pal_posix.h b/src/pal/pal_posix.h
index 6fbecad..ba1f489 100644
--- a/src/pal/pal_posix.h
+++ b/src/pal/pal_posix.h
@@ -135,6 +135,9 @@ namespace snmalloc
     {
       SNMALLOC_ASSERT(is_aligned_block<OS::page_size>(p, size));
 #ifdef USE_POSIX_COMMIT_CHECKS
+      // Fill memory so that when we switch the pages back on we don't make
+      // assumptions on the content.
+      memset(p, 0x5a, size);
       mprotect(p, size, PROT_NONE);
 #else
       UNUSED(p);