89 lines
3.4 KiB
C++
89 lines
3.4 KiB
C++
//===-- asan_poisoning.h ----------------------------------------*- C++ -*-===//
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of AddressSanitizer, an address sanity checker.
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//
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// Shadow memory poisoning by ASan RTL and by user application.
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//===----------------------------------------------------------------------===//
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#include "asan_interceptors.h"
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#include "asan_internal.h"
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#include "asan_mapping.h"
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#include "sanitizer_common/sanitizer_flags.h"
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namespace __asan {
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// Poisons the shadow memory for "size" bytes starting from "addr".
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void PoisonShadow(uptr addr, uptr size, u8 value);
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// Poisons the shadow memory for "redzone_size" bytes starting from
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// "addr + size".
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void PoisonShadowPartialRightRedzone(uptr addr,
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uptr size,
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uptr redzone_size,
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u8 value);
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// Fast versions of PoisonShadow and PoisonShadowPartialRightRedzone that
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// assume that memory addresses are properly aligned. Use in
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// performance-critical code with care.
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ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size,
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u8 value) {
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DCHECK(flags()->poison_heap);
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uptr PageSize = GetPageSizeCached();
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uptr shadow_beg = MEM_TO_SHADOW(aligned_beg);
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uptr shadow_end = MEM_TO_SHADOW(
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aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1;
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// FIXME: Page states are different on Windows, so using the same interface
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// for mapping shadow and zeroing out pages doesn't "just work", so we should
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// probably provide higher-level interface for these operations.
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// For now, just memset on Windows.
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if (value ||
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SANITIZER_WINDOWS == 1 ||
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shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) {
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REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg);
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} else {
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uptr page_beg = RoundUpTo(shadow_beg, PageSize);
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uptr page_end = RoundDownTo(shadow_end, PageSize);
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if (page_beg >= page_end) {
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REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg);
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} else {
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if (page_beg != shadow_beg) {
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REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg);
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}
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if (page_end != shadow_end) {
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REAL(memset)((void *)page_end, 0, shadow_end - page_end);
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}
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void *res = MmapFixedNoReserve(page_beg, page_end - page_beg);
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CHECK_EQ(page_beg, res);
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}
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}
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}
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ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone(
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uptr aligned_addr, uptr size, uptr redzone_size, u8 value) {
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DCHECK(flags()->poison_heap);
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bool poison_partial = flags()->poison_partial;
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u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr);
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for (uptr i = 0; i < redzone_size; i += SHADOW_GRANULARITY, shadow++) {
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if (i + SHADOW_GRANULARITY <= size) {
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*shadow = 0; // fully addressable
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} else if (i >= size) {
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*shadow = (SHADOW_GRANULARITY == 128) ? 0xff : value; // unaddressable
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} else {
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// first size-i bytes are addressable
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*shadow = poison_partial ? static_cast<u8>(size - i) : 0;
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}
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}
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}
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// Calls __sanitizer::FlushUnneededShadowMemory() on
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// [MemToShadow(p), MemToShadow(p+size)] with proper rounding.
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void FlushUnneededASanShadowMemory(uptr p, uptr size);
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} // namespace __asan
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