1 files changed, 36 insertions, 0 deletions
diff --git a/test/msan/allocator_mapping.cc b/test/msan/allocator_mapping.cc
new file mode 100644
index 000000000000..f47d9a63e09f
--- /dev/null
+++ b/test/msan/allocator_mapping.cc
@@ -0,0 +1,36 @@
+// Test that a module constructor can not map memory over the MSan heap
+// (without MAP_FIXED, of course). Current implementation ensures this by
+// mapping the heap early, in __msan_init.
+//
+// RUN: %clangxx_msan -O0 %s -o %t_1
+// RUN: %clangxx_msan -O0 -DHEAP_ADDRESS=$(%run %t_1) %s -o %t_2 && %run %t_2
+//
+// This test only makes sense for the 64-bit allocator. The 32-bit allocator
+// does not have a fixed mapping. Exclude platforms that use the 32-bit
+// allocator.
+// UNSUPPORTED: mips64,aarch64
+
+#include <assert.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <stdlib.h>
+
+#ifdef HEAP_ADDRESS
+struct A {
+  A() {
+    void *const hint = reinterpret_cast<void *>(HEAP_ADDRESS);
+    void *p = mmap(hint, 4096, PROT_READ | PROT_WRITE,
+                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    // This address must be already mapped. Check that mmap() succeeds, but at a
+    // different address.
+    assert(p != reinterpret_cast<void *>(-1));
+    assert(p != hint);
+  }
+} a;
+#endif
+
+int main() {
+  void *p = malloc(10);
+  printf("0x%zx\n", reinterpret_cast<size_t>(p) & (~0xfff));
+  free(p);
+}