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