[ASAN] Add mmap and munmap interceptor in ASAN

[vitalybuka]

compiler-rt/lib/asan/asan_interceptors.cpp

153

why do you drop errno = errno_EINVAL; cases?
Can we keep as close as possible to hwasan_interceptors.cpp one?

177

I guess PoisonShadow will work the same way
maybe use PoisonShadow for consistency?

compiler-rt/test/asan/TestCases/mapped_mem_interceptors.c

27

__asan_poison_memory_region() before munmap

33

__asan_poison_memory_region() before mmap(r, size,

46

No newline at end of file

[kstoimenov]

Addressed comments.

compiler-rt/lib/asan/asan_interceptors.cpp

153

I made this change because compiler-rt/test/asan/TestCases/Linux/cuda_test.cpp failed. HWASAN implementation was somewhat restrictive because it wouldn't allow mmapping of any memory which is not managed by the sanitizers. This implementation will only manipulate shadow memory if the region is sanitizer managed.

[vitalybuka]

compiler-rt/lib/asan/asan_interceptors.cpp

159–161

174–178

for consistency with errno_EINVAL in mmap

[kstoimenov]

Addressed comments.

compiler-rt/lib/asan/asan_interceptors.cpp

 #include "asan_mapping.h"
 #include "asan_poisoning.h"
 #include "asan_report.h"
 #include "asan_stack.h"
 #include "asan_stats.h"
 #include "asan_suppressions.h"
 #include "asan_thread.h"
 #include "lsan/lsan_common.h"
+#include "sanitizer_common/sanitizer_errno.h"
 #include "sanitizer_common/sanitizer_internal_defs.h"
 #include "sanitizer_common/sanitizer_libc.h"
 
 // There is no general interception at all on Fuchsia.
 // Only the functions in asan_interceptors_memintrinsics.cpp are
 // really defined to replace libc functions.
 #if !SANITIZER_FUCHSIA
 

 #  define COMMON_INTERCEPTOR_GET_TLS_RANGE(begin, end) \
     if (AsanThread *t = GetCurrentThread()) {          \
       *begin = t->tls_begin();                         \
       *end = t->tls_end();                             \
     } else {                                           \
       *begin = *end = 0;                               \
     }
 
+template <class Mmap>
+static void* mmap_interceptor(Mmap real_mmap, void *addr, SIZE_T length,
+                              int prot, int flags, int fd, OFF64_T offset) {
+  void *res = real_mmap(addr, length, prot, flags, fd, offset);
+  if (length && res != (void *)-1) {
+    const uptr beg = reinterpret_cast<uptr>(res);
+    DCHECK(IsAligned(beg, GetPageSize()));
+    SIZE_T rounded_length = RoundUpTo(length, GetPageSize());
+    // Only unpoison shadow if it's an ASAN managed address.
+    if (AddrIsInMem(beg) && AddrIsInMem(beg + rounded_length - 1))
+      PoisonShadow(beg, RoundUpTo(length, GetPageSize()), 0);
+  }
+  return res;
+}
+
+template <class Munmap>
+static int munmap_interceptor(Munmap real_munmap, void *addr, SIZE_T length) {
+  // We should not tag if munmap fail, but it's to late to tag after
+  // real_munmap, as the pages could be mmaped by another thread.
+  const uptr beg = reinterpret_cast<uptr>(addr);
+  if (length && IsAligned(beg, GetPageSize())) {
+    SIZE_T rounded_length = RoundUpTo(length, GetPageSize());
+    // Protect from unmapping the shadow.
+    if (AddrIsInMem(beg) && AddrIsInMem(beg + rounded_length - 1))
+      PoisonShadow(beg, rounded_length, 0);
+  }
+  return real_munmap(addr, length);
+}
+
+#  define COMMON_INTERCEPTOR_MMAP_IMPL(ctx, mmap, addr, length, prot, flags,   \
+                                     fd, offset)                               \
+  do {                                                                         \
+    (void)(ctx);                                                               \
+    return mmap_interceptor(REAL(mmap), addr, sz, prot, flags, fd, off);       \
+  } while (false)
+
+#  define COMMON_INTERCEPTOR_MUNMAP_IMPL(ctx, addr, length)                    \
+  do {                                                                         \
+    (void)(ctx);                                                               \
+    return munmap_interceptor(REAL(munmap), addr, sz);                         \
+  } while (false)
+
 #if CAN_SANITIZE_LEAKS
 #define COMMON_INTERCEPTOR_STRERROR()                       \
   __lsan::ScopedInterceptorDisabler disabler
 #endif
 
 #include "sanitizer_common/sanitizer_common_interceptors.inc"
 #include "sanitizer_common/sanitizer_signal_interceptors.inc"
 

compiler-rt/test/asan/TestCases/mapped_mem_interceptors.c

+// Test for mmap/munmap interceptors.
+// RUN: %clang_asan  %s -o %t
+// RUN: %run %t 2>&1
+
+#include <assert.h>
+#include <sanitizer/asan_interface.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+int main(int argc, char **argv) {
+  int size = 4096;
+  int val = 42;
+
+  // Get any mmaped pointer.
+  void *r =
+      mmap(0, size, PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
+  assert(r != MAP_FAILED);
+
+  // Make sure the memory is unpoisoned.
+  if (__asan_region_is_poisoned(r, size) != 0) {
+    fprintf(stderr, "Memory returned by mmap should be unpoisoned.\n");
+    abort();
+  }
+
+  // First munmmap and then mmap the same pointer using MAP_FIXED.
+  __asan_poison_memory_region(r, size);
+  munmap(r, size);
+  if (__asan_region_is_poisoned(r, size) != 0) {
+    fprintf(stderr, "Shadow memory was not cleaned by munmap.\n");
+    abort();
+  }
+  __asan_poison_memory_region(r, size);
+  void *p = mmap(r, size, PROT_READ | PROT_WRITE,
+                 MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
+  assert(r == p);
+
+  // Make sure the memory is unpoisoned.
+  if (__asan_region_is_poisoned(r, size) != 0) {
+    fprintf(stderr, "Memory returned by mmap should be unpoisoned.\n");
+    abort();
+  }
+
+  return 0;
+}