llvm-project/compiler-rt/test/msan/strlen_of_shadow.cc

// RUN: %clangxx_msan -O0 %s -o %t && %run %t

// Check that strlen() and similar intercepted functions can be called on shadow
// memory.

#include <assert.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "test.h"

const char *mem_to_shadow(const char *p) {
#if defined(__x86_64__)
  return (char *)((uintptr_t)p ^ 0x500000000000ULL);
#elif defined (__mips64)
  return (char *)((uintptr_t)p & ~0x4000000000ULL);
#elif defined(__powerpc64__)
#define LINEARIZE_MEM(mem) \
  (((uintptr_t)(mem) & ~0x200000000000ULL) ^ 0x100000000000ULL)
  return (char *)(LINEARIZE_MEM(p) + 0x080000000000ULL);
#elif defined(__aarch64__)
  unsigned long vma = SystemVMA();

#define LINEARIZE_MEM_39(mem) \
  (((uintptr_t)(mem) & ~0x7C00000000ULL) ^ 0x100000000ULL)
#define LINEARIZE_MEM_42(mem) \
  (((uintptr_t)(mem) & ~0x3E000000000ULL) ^ 0x1000000000ULL)

  if (vma == 39)
    return (char *)(LINEARIZE_MEM_39(p) + 0x4000000000ULL);
  else if (vma == 42)
    return (char *)(LINEARIZE_MEM_42(p) + 0x10000000000ULL);
  else {
    fprintf(stderr, "unsupported vma: %lu\n", vma);
    exit(1);
  }
#endif
}

int main(void) {
  const char *s = "abcdef";
  assert(strlen(s) == 6);
  assert(strlen(mem_to_shadow(s)) == 0);

  char *t = new char[42];
  t[41] = 0;
  assert(strlen(mem_to_shadow(t)) == 41);
  return 0;
}