[sanitizer] add a function MmapNoAccess that mmaps a protected region *somewhere*; use MmapNoAccess in the Allocator when SpaceBeg is not a constant. In this mode the allocator will be a bit more hardened

llvm-svn: 267256

compiler-rt/lib/sanitizer_common/sanitizer_allocator.h

@@ -327,8 +327,8 @@ class SizeClassAllocator64 {
       CHECK_EQ(kSpaceBeg, reinterpret_cast<uptr>(
                               MmapFixedNoAccess(kSpaceBeg, kSpaceSize)));
     } else {
-      NonConstSpaceBeg = reinterpret_cast<uptr>(
-          MmapFixedNoAccess(0, kSpaceSize + AdditionalSize()));
+      NonConstSpaceBeg =
+          reinterpret_cast<uptr>(MmapNoAccess(kSpaceSize + AdditionalSize()));
       CHECK_NE(NonConstSpaceBeg, ~(uptr)0);
     }
     MapWithCallback(SpaceEnd(), AdditionalSize());

compiler-rt/lib/sanitizer_common/sanitizer_common.h

@@ -85,6 +85,7 @@ void *MmapFixedNoReserve(uptr fixed_addr, uptr size,
 void *MmapNoReserveOrDie(uptr size, const char *mem_type);
 void *MmapFixedOrDie(uptr fixed_addr, uptr size);
 void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name = nullptr);
+void *MmapNoAccess(uptr size);
 // Map aligned chunk of address space; size and alignment are powers of two.
 void *MmapAlignedOrDie(uptr size, uptr alignment, const char *mem_type);
 // Disallow access to a memory range.  Use MmapFixedNoAccess to allocate an

compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc

@@ -279,6 +279,11 @@ void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
                                0);
 }
 
+void *MmapNoAccess(uptr size) {
+  unsigned flags = MAP_PRIVATE | MAP_ANON | MAP_NORESERVE;
+  return (void *)internal_mmap(nullptr, size, PROT_NONE, flags, -1, 0);
+}
+
 // This function is defined elsewhere if we intercepted pthread_attr_getstack.
 extern "C" {
 SANITIZER_WEAK_ATTRIBUTE int

compiler-rt/lib/sanitizer_common/sanitizer_win.cc

@@ -211,6 +211,11 @@ void *MmapFixedNoAccess(uptr fixed_addr, uptr size, const char *name) {
   return res;
 }
 
+void *MmapNoAccess(uptr size) {
+  // FIXME: unsupported.
+  return nullptr;
+}
+
 bool MprotectNoAccess(uptr addr, uptr size) {
   DWORD old_protection;
   return VirtualProtect((LPVOID)addr, size, PAGE_NOACCESS, &old_protection);

compiler-rt/lib/sanitizer_common/tests/sanitizer_allocator_testlib.cc

@@ -37,7 +37,8 @@ namespace {
 static const uptr kAllocatorSpace = 0x600000000000ULL;
 static const uptr kAllocatorSize  =  0x10000000000ULL;  // 1T.
 
-typedef SizeClassAllocator64<kAllocatorSpace, kAllocatorSize, 0,
+// typedef SizeClassAllocator64<kAllocatorSpace, kAllocatorSize, 0,
+typedef SizeClassAllocator64<~(uptr)0, kAllocatorSize, 0,
   CompactSizeClassMap> PrimaryAllocator;
 typedef SizeClassAllocatorLocalCache<PrimaryAllocator> AllocatorCache;
 typedef LargeMmapAllocator<> SecondaryAllocator;