1 files changed, 28 insertions, 0 deletions
diff --git a/test/msan/mmap_below_shadow.cc b/test/msan/mmap_below_shadow.cc
new file mode 100644
index 000000000000..4b5890ba0fb8
--- /dev/null
+++ b/test/msan/mmap_below_shadow.cc
@@ -0,0 +1,28 @@
+// Test mmap behavior when map address is below shadow range.
+// With MAP_FIXED, we return EINVAL.
+// Without MAP_FIXED, we ignore the address hint and map somewhere in
+// application range.
+
+// RUN: %clangxx_msan -m64 -O0 -DFIXED=0 %s -o %t && %run %t
+// RUN: %clangxx_msan -m64 -O0 -DFIXED=1 %s -o %t && %run %t
+// RUN: %clangxx_msan -m64 -O0 -DFIXED=0 -D_FILE_OFFSET_BITS=64 %s -o %t && %run %t
+// RUN: %clangxx_msan -m64 -O0 -DFIXED=1 -D_FILE_OFFSET_BITS=64 %s -o %t && %run %t
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <sys/mman.h>
+
+int main(void) {
+  // Hint address just below shadow.
+  uintptr_t hint = 0x4f0000000000ULL;
+  const uintptr_t app_start = 0x600000000000ULL;
+  uintptr_t p = (uintptr_t)mmap(
+      (void *)hint, 4096, PROT_WRITE,
+      MAP_PRIVATE | MAP_ANONYMOUS | (FIXED ? MAP_FIXED : 0), -1, 0);
+  if (FIXED)
+    assert(p == (uintptr_t)-1 && errno == EINVAL);
+  else
+    assert(p >= app_start);
+  return 0;
+}