libsanitizer/hwasan/hwasan_poisoning.cpp

   1 //===-- hwasan_poisoning.cpp ------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of HWAddressSanitizer.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "hwasan_poisoning.h"
  14
  15 #include "hwasan_mapping.h"
  16 #include "interception/interception.h"
  17 #include "sanitizer_common/sanitizer_common.h"
  18 #include "sanitizer_common/sanitizer_linux.h"
  19
  20 namespace __hwasan {
  21
  22 uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
  23   CHECK(IsAligned(p, kShadowAlignment));
  24   CHECK(IsAligned(size, kShadowAlignment));
  25   uptr shadow_start = MemToShadow(p);
  26   uptr shadow_size = MemToShadowSize(size);
  27
  28   uptr page_size = GetPageSizeCached();
  29   uptr page_start = RoundUpTo(shadow_start, page_size);
  30   uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size);
  31   uptr threshold = common_flags()->clear_shadow_mmap_threshold;
  32   if (SANITIZER_LINUX &&
  33       UNLIKELY(page_end >= page_start + threshold && tag == 0)) {
  34     internal_memset((void *)shadow_start, tag, page_start - shadow_start);
  35     internal_memset((void *)page_end, tag,
  36                     shadow_start + shadow_size - page_end);
  37     // For an anonymous private mapping MADV_DONTNEED will return a zero page on
  38     // Linux.
  39     ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end);
  40   } else {
  41     internal_memset((void *)shadow_start, tag, shadow_size);
  42   }
  43   return AddTagToPointer(p, tag);
  44 }
  45
  46 uptr TagMemory(uptr p, uptr size, tag_t tag) {
  47   uptr start = RoundDownTo(p, kShadowAlignment);
  48   uptr end = RoundUpTo(p + size, kShadowAlignment);
  49   return TagMemoryAligned(start, end - start, tag);
  50 }
  51
  52 }  // namespace __hwasan