1 //===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 //
12 // Shadow memory poisoning by ASan RTL and by user application.
13 //===----------------------------------------------------------------------===//
14
15 #include "asan_interceptors.h"
16 #include "asan_internal.h"
17 #include "asan_mapping.h"
18 #include "sanitizer_common/sanitizer_flags.h"
19
20 namespace __asan {
21
22 // Poisons the shadow memory for "size" bytes starting from "addr".
23 void PoisonShadow(uptr addr, uptr size, u8 value);
24
25 // Poisons the shadow memory for "redzone_size" bytes starting from
26 // "addr + size".
27 void PoisonShadowPartialRightRedzone(uptr addr,
28 uptr size,
29 uptr redzone_size,
30 u8 value);
31
32 // Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
33 // assume that memory addresses are properly aligned. Use in
34 // performance-critical code with care.
FastPoisonShadow(uptr aligned_beg,uptr aligned_size,u8 value)35 ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
36 u8 value) {
37 DCHECK(flags()->poison_heap);
38 uptr PageSize = GetPageSizeCached();
39 uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
40 uptr shadow_end = MEM_TO_SHADOW(
41 aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1;
42 // FIXME: Page states are different on Windows, so using the same interface
43 // for mapping shadow and zeroing out pages doesn't "just work", so we should
44 // probably provide higher-level interface for these operations.
45 // For now, just memset on Windows.
46 if (value ||
47 SANITIZER_WINDOWS == 1 ||
48 shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
49 REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
50 } else {
51 uptr page_beg = RoundUpTo(shadow_beg, PageSize);
52 uptr page_end = RoundDownTo(shadow_end, PageSize);
53
54 if (page_beg >= page_end) {
55 REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
56 } else {
57 if (page_beg != shadow_beg) {
58 REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
59 }
60 if (page_end != shadow_end) {
61 REAL(memset)((void *)page_end, 0, shadow_end - page_end);
62 }
63 void *res = MmapFixedNoReserve(page_beg, page_end - page_beg);
64 CHECK_EQ(page_beg, res);
65 }
66 }
67 }
68
FastPoisonShadowPartialRightRedzone(uptr aligned_addr,uptr size,uptr redzone_size,u8 value)69 ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
70 uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
71 DCHECK(flags()->poison_heap);
72 bool poison_partial = flags()->poison_partial;
73 u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
74 for (uptr i = 0; i < redzone_size; i += SHADOW_GRANULARITY, shadow++) {
75 if (i + SHADOW_GRANULARITY <= size) {
76 *shadow = 0; // fully addressable
77 } else if (i >= size) {
78 *shadow = (SHADOW_GRANULARITY == 128) ? 0xff : value; // unaddressable
79 } else {
80 // first size-i bytes are addressable
81 *shadow = poison_partial ? static_cast<u8>(size - i) : 0;
82 }
83 }
84 }
85
86 // Calls __sanitizer::FlushUnneededShadowMemory() on
87 // [MemToShadow(p), MemToShadow(p+size)] with proper rounding.
88 void FlushUnneededASanShadowMemory(uptr p, uptr size);
89
90 } // namespace __asan
91