1 //===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Shadow memory poisoning by ASan RTL and by user application.
12 //===----------------------------------------------------------------------===//
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"
22 // Enable/disable memory poisoning.
23 void SetCanPoisonMemory(bool value
);
24 bool CanPoisonMemory();
26 // Poisons the shadow memory for "size" bytes starting from "addr".
27 void PoisonShadow(uptr addr
, uptr size
, u8 value
);
29 // Poisons the shadow memory for "redzone_size" bytes starting from
31 void PoisonShadowPartialRightRedzone(uptr addr
,
36 // Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
37 // assume that memory addresses are properly aligned. Use in
38 // performance-critical code with care.
39 ALWAYS_INLINE
void FastPoisonShadow(uptr aligned_beg
, uptr aligned_size
,
41 DCHECK(!value
|| CanPoisonMemory());
43 __sanitizer_fill_shadow(aligned_beg
, aligned_size
, value
,
44 common_flags()->clear_shadow_mmap_threshold
);
46 uptr shadow_beg
= MEM_TO_SHADOW(aligned_beg
);
47 uptr shadow_end
= MEM_TO_SHADOW(
48 aligned_beg
+ aligned_size
- 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 // RTEMS doesn't have have pages, let alone a fast way to zero
55 // them, so default to memset.
56 SANITIZER_RTEMS
== 1 ||
57 shadow_end
- shadow_beg
< common_flags()->clear_shadow_mmap_threshold
) {
58 REAL(memset
)((void*)shadow_beg
, value
, shadow_end
- shadow_beg
);
60 uptr page_size
= GetPageSizeCached();
61 uptr page_beg
= RoundUpTo(shadow_beg
, page_size
);
62 uptr page_end
= RoundDownTo(shadow_end
, page_size
);
64 if (page_beg
>= page_end
) {
65 REAL(memset
)((void *)shadow_beg
, 0, shadow_end
- shadow_beg
);
67 if (page_beg
!= shadow_beg
) {
68 REAL(memset
)((void *)shadow_beg
, 0, page_beg
- shadow_beg
);
70 if (page_end
!= shadow_end
) {
71 REAL(memset
)((void *)page_end
, 0, shadow_end
- page_end
);
73 ReserveShadowMemoryRange(page_beg
, page_end
- 1, nullptr);
76 #endif // SANITIZER_FUCHSIA
79 ALWAYS_INLINE
void FastPoisonShadowPartialRightRedzone(
80 uptr aligned_addr
, uptr size
, uptr redzone_size
, u8 value
) {
81 DCHECK(CanPoisonMemory());
82 bool poison_partial
= flags()->poison_partial
;
83 u8
*shadow
= (u8
*)MEM_TO_SHADOW(aligned_addr
);
84 for (uptr i
= 0; i
< redzone_size
; i
+= SHADOW_GRANULARITY
, shadow
++) {
85 if (i
+ SHADOW_GRANULARITY
<= size
) {
86 *shadow
= 0; // fully addressable
87 } else if (i
>= size
) {
88 *shadow
= (SHADOW_GRANULARITY
== 128) ? 0xff : value
; // unaddressable
90 // first size-i bytes are addressable
91 *shadow
= poison_partial
? static_cast<u8
>(size
- i
) : 0;
96 // Calls __sanitizer::ReleaseMemoryPagesToOS() on
97 // [MemToShadow(p), MemToShadow(p+size)].
98 void FlushUnneededASanShadowMemory(uptr p
, uptr size
);
100 } // namespace __asan