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//===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Shadow memory poisoning by ASan RTL and by user application.
//===----------------------------------------------------------------------===//
#include "asan_interceptors.h"
#include "asan_internal.h"
#include "asan_mapping.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_platform.h"
namespace __asan {
// Enable/disable memory poisoning.
void SetCanPoisonMemory(bool value);
bool CanPoisonMemory();
// Poisons the shadow memory for "size" bytes starting from "addr".
void PoisonShadow(uptr addr, uptr size, u8 value);
// Poisons the shadow memory for "redzone_size" bytes starting from
// "addr + size".
void PoisonShadowPartialRightRedzone(uptr addr,
uptr size,
uptr redzone_size,
u8 value);
// Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
// assume that memory addresses are properly aligned. Use in
// performance-critical code with care.
ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
u8 value) {
DCHECK(!value || CanPoisonMemory());
#if SANITIZER_FUCHSIA
__sanitizer_fill_shadow(aligned_beg, aligned_size, value,
common_flags()->clear_shadow_mmap_threshold);
#else
uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
uptr shadow_end =
MEM_TO_SHADOW(aligned_beg + aligned_size - ASAN_SHADOW_GRANULARITY) + 1;
// FIXME: Page states are different on Windows, so using the same interface
// for mapping shadow and zeroing out pages doesn't "just work", so we should
// probably provide higher-level interface for these operations.
// For now, just memset on Windows.
if (value || SANITIZER_WINDOWS == 1 ||
shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
} else {
uptr page_size = GetPageSizeCached();
uptr page_beg = RoundUpTo(shadow_beg, page_size);
uptr page_end = RoundDownTo(shadow_end, page_size);
if (page_beg >= page_end) {
REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
} else {
if (page_beg != shadow_beg) {
REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
}
if (page_end != shadow_end) {
REAL(memset)((void *)page_end, 0, shadow_end - page_end);
}
ReserveShadowMemoryRange(page_beg, page_end - 1, nullptr);
}
}
#endif // SANITIZER_FUCHSIA
}
ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
DCHECK(CanPoisonMemory());
bool poison_partial = flags()->poison_partial;
u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
for (uptr i = 0; i < redzone_size; i += ASAN_SHADOW_GRANULARITY, shadow++) {
if (i + ASAN_SHADOW_GRANULARITY <= size) {
*shadow = 0; // fully addressable
} else if (i >= size) {
*shadow =
(ASAN_SHADOW_GRANULARITY == 128) ? 0xff : value; // unaddressable
} else {
// first size-i bytes are addressable
*shadow = poison_partial ? static_cast<u8>(size - i) : 0;
}
}
}
// Calls __sanitizer::ReleaseMemoryPagesToOS() on
// [MemToShadow(p), MemToShadow(p+size)].
void FlushUnneededASanShadowMemory(uptr p, uptr size);
} // namespace __asan
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