compiler-rt/test/sanitizer_common/TestCases/Linux/mmap_56bit_test.c

   1 // RUN: %clangxx %s -pie -fPIE -o %t && %run %t
   2 // REQUIRES: x86_64-target-arch
   3
   4 #include <assert.h>
   5 #include <stdio.h>
   6 #include <sys/mman.h>
   7
   8 int main() {
   9     for (int j = 0; j < 1024; j++) {
  10         // Try 1TB offsets. This attempts to find memory addresses where the
  11         // shadow mappings - which assume a 47-bit address space - are invalid.
  12         unsigned long long target = (1ULL << 56) - (2 * 4096) - (j * (1ULL << 40));
  13
  14         // Since we don't use MAP_FIXED, mmap might return an address that is
  15         // lower in the address space (due to sanitizer and/or kernel limits).
  16         // That is fine - if the app is also restricted from making high
  17         // allocations, then they are safe.
  18         char* ptr = (char*) mmap ((void*) target, 4096, PROT_READ | PROT_WRITE,
  19                                   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  20         printf ("Allocated at %p\n", ptr);
  21
  22         assert (ptr != MAP_FAILED);
  23         for (int i = 0; i < 100; i++) {
  24             ptr [i] = 0;
  25         }
  26         munmap (ptr, 4096);
  27     }
  28
  29     return 0;
  30 }