1 //===-- asan_poisoning.h ----------------------------------------*- 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 AddressSanitizer, an address sanity checker.
10 //
11 // Shadow memory poisoning by ASan RTL and by user application.
12 //===----------------------------------------------------------------------===//
13
14 #include "asan_interceptors.h"
15 #include "asan_internal.h"
16 #include "asan_mapping.h"
17 #include "sanitizer_common/sanitizer_flags.h"
18 #include "sanitizer_common/sanitizer_platform.h"
19
20 namespace __asan {
21
22 // Enable/disable memory poisoning.
23 void SetCanPoisonMemory(bool value);
24 bool CanPoisonMemory();
25
26 // Poisons the shadow memory for "size" bytes starting from "addr".
27 void PoisonShadow(uptr addr, uptr size, u8 value);
28
29 // Poisons the shadow memory for "redzone_size" bytes starting from
30 // "addr + size".
31 void PoisonShadowPartialRightRedzone(uptr addr,
32 uptr size,
33 uptr redzone_size,
34 u8 value);
35
36 // Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
37 // assume that memory addresses are properly aligned. Use in
38 // performance-critical code with care.
FastPoisonShadow(uptr aligned_beg,uptr aligned_size,u8 value)39 ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
40 u8 value) {
41 DCHECK(!value || CanPoisonMemory());
42 #if SANITIZER_FUCHSIA
43 __sanitizer_fill_shadow(aligned_beg, aligned_size, value,
44 common_flags()->clear_shadow_mmap_threshold);
45 #else
46 uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
47 uptr shadow_end =
48 MEM_TO_SHADOW(aligned_beg + aligned_size - ASAN_SHADOW_GRANULARITY) + 1;
49 // FIXME: Page states are different on Windows, so using the same interface
50 // for mapping shadow and zeroing out pages doesn't "just work", so we should
51 // probably provide higher-level interface for these operations.
52 // For now, just memset on Windows.
53 if (value || SANITIZER_WINDOWS == 1 ||
54 shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
55 REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
56 } else {
57 uptr page_size = GetPageSizeCached();
58 uptr page_beg = RoundUpTo(shadow_beg, page_size);
59 uptr page_end = RoundDownTo(shadow_end, page_size);
60
61 if (page_beg >= page_end) {
62 REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
63 } else {
64 if (page_beg != shadow_beg) {
65 REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
66 }
67 if (page_end != shadow_end) {
68 REAL(memset)((void *)page_end, 0, shadow_end - page_end);
69 }
70 ReserveShadowMemoryRange(page_beg, page_end - 1, nullptr);
71 }
72 }
73 #endif // SANITIZER_FUCHSIA
74 }
75
FastPoisonShadowPartialRightRedzone(uptr aligned_addr,uptr size,uptr redzone_size,u8 value)76 ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
77 uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
78 DCHECK(CanPoisonMemory());
79 bool poison_partial = flags()->poison_partial;
80 u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
81 for (uptr i = 0; i < redzone_size; i += ASAN_SHADOW_GRANULARITY, shadow++) {
82 if (i + ASAN_SHADOW_GRANULARITY <= size) {
83 *shadow = 0; // fully addressable
84 } else if (i >= size) {
85 *shadow =
86 (ASAN_SHADOW_GRANULARITY == 128) ? 0xff : value; // unaddressable
87 } else {
88 // first size-i bytes are addressable
89 *shadow = poison_partial ? static_cast<u8>(size - i) : 0;
90 }
91 }
92 }
93
94 // Calls __sanitizer::ReleaseMemoryPagesToOS() on
95 // [MemToShadow(p), MemToShadow(p+size)].
96 void FlushUnneededASanShadowMemory(uptr p, uptr size);
97
98 } // namespace __asan
99