1 //===-- asan_poisoning.h ----------------------------------------*- C++ -*-===// 2 // 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 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file is a part of AddressSanitizer, an address sanity checker. 10 // 11 // Shadow memory poisoning by ASan RTL and by user application. 12 //===----------------------------------------------------------------------===// 13 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" 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(!value || CanPoisonMemory()); 42 #if SANITIZER_FUCHSIA 43 __sanitizer_fill_shadow(aligned_beg, aligned_size, value, 44 common_flags()->clear_shadow_mmap_threshold); 45 #else 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); 59 } else { 60 uptr page_size = GetPageSizeCached(); 61 uptr page_beg = RoundUpTo(shadow_beg, page_size); 62 uptr page_end = RoundDownTo(shadow_end, page_size); 63 64 if (page_beg >= page_end) { 65 REAL(memset)((void *)shadow_beg, 0, shadow_end - shadow_beg); 66 } else { 67 if (page_beg != shadow_beg) { 68 REAL(memset)((void *)shadow_beg, 0, page_beg - shadow_beg); 69 } 70 if (page_end != shadow_end) { 71 REAL(memset)((void *)page_end, 0, shadow_end - page_end); 72 } 73 ReserveShadowMemoryRange(page_beg, page_end - 1, nullptr); 74 } 75 } 76 #endif // SANITIZER_FUCHSIA 77 } 78 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 89 } else { 90 // first size-i bytes are addressable 91 *shadow = poison_partial ? static_cast<u8>(size - i) : 0; 92 } 93 } 94 } 95 96 // Calls __sanitizer::ReleaseMemoryPagesToOS() on 97 // [MemToShadow(p), MemToShadow(p+size)]. 98 void FlushUnneededASanShadowMemory(uptr p, uptr size); 99 100 } // namespace __asan 101