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.
microsoft · Nov 10, 2020 · 3ca29d6 · 3ca29d6
1 parent 01b282a
commit 3ca29d6
Showing 1 changed file with 3 additions and 0 deletions.
diff --git 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);