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 // 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. 39 ALWAYS_INLINE void FastPoisonShadow(uptr aligned_beg, uptr aligned_size, 40 u8 value) { 41 DCHECK(CanPoisonMemory()); 42 uptr shadow_beg = MEM_TO_SHADOW(aligned_beg); 43 uptr shadow_end = MEM_TO_SHADOW( 44 aligned_beg + aligned_size - SHADOW_GRANULARITY) + 1; 45 // FIXME: Page states are different on Windows, so using the same interface 46 // for mapping shadow and zeroing out pages doesn't "just work", so we should 47 // probably provide higher-level interface for these operations. 48 // For now, just memset on Windows. 49 if (value || 50 SANITIZER_WINDOWS == 1 || 51 shadow_end - shadow_beg < common_flags()->clear_shadow_mmap_threshold) { 52 REAL(memset)((void*)shadow_beg, value, shadow_end - shadow_beg); 53 } else { 54 uptr page_size = GetPageSizeCached(); 55 uptr page_beg = RoundUpTo(shadow_beg, page_size); 56 uptr page_end = RoundDownTo(shadow_end, page_size); 57 58 if (page_beg >= page_end) { 59 REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg); 60 } else { 61 if (page_beg != shadow_beg) { 62 REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg); 63 } 64 if (page_end != shadow_end) { 65 REAL(memset)((void *)page_end, 0, shadow_end - page_end); 66 } 67 ReserveShadowMemoryRange(page_beg, page_end - 1, nullptr); 68 } 69 } 70 } 71 72 ALWAYS_INLINE void FastPoisonShadowPartialRightRedzone( 73 uptr aligned_addr, uptr size, uptr redzone_size, u8 value) { 74 DCHECK(CanPoisonMemory()); 75 bool poison_partial = flags()->poison_partial; 76 u8 *shadow = (u8*)MEM_TO_SHADOW(aligned_addr); 77 for (uptr i = 0; i < redzone_size; i += SHADOW_GRANULARITY, shadow++) { 78 if (i + SHADOW_GRANULARITY <= size) { 79 *shadow = 0; // fully addressable 80 } else if (i >= size) { 81 *shadow = (SHADOW_GRANULARITY == 128) ? 0xff : value; // unaddressable 82 } else { 83 // first size-i bytes are addressable 84 *shadow = poison_partial ? static_cast<u8>(size - i) : 0; 85 } 86 } 87 } 88 89 // Calls __sanitizer::FlushUnneededShadowMemory() on 90 // [MemToShadow(p), MemToShadow(p+size)] with proper rounding. 91 void FlushUnneededASanShadowMemory(uptr p, uptr size); 92 93 } // namespace __asan 94
