cppgc: Make sure pages returned to OS are unpoisoned

Otherwice, accesses in subsequent allocations may fail.

Bug: chromium:1101152
Change-Id: Ie8bd87e3ef68b532c8fa6ef85f757c930cbe35fd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2300485Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68883}

src/heap/cppgc/page-memory.cc

@@ -5,6 +5,7 @@
 #include "src/heap/cppgc/page-memory.h"
 
 #include "src/base/macros.h"
+#include "src/heap/cppgc/sanitizers.h"
 
 namespace cppgc {
 namespace internal {
@@ -60,6 +61,8 @@ MemoryRegion ReserveMemoryRegion(PageAllocator* allocator,
 
 void FreeMemoryRegion(PageAllocator* allocator,
                       const MemoryRegion& reserved_region) {
+  // Make sure pages returned to OS are unpoisoned.
+  ASAN_UNPOISON_MEMORY_REGION(reserved_region.base(), reserved_region.size());
   allocator->FreePages(reserved_region.base(), reserved_region.size());
 }