asan_globals.cc revision dfeef67b23ba92bbee598293164ee20078f633a1
1//===-- asan_globals.cc ---------------------------------------------------===// 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// Handle globals. 13//===----------------------------------------------------------------------===// 14#include "asan_interceptors.h" 15#include "asan_internal.h" 16#include "asan_mapping.h" 17#include "asan_poisoning.h" 18#include "asan_report.h" 19#include "asan_stack.h" 20#include "asan_stats.h" 21#include "asan_thread.h" 22#include "sanitizer_common/sanitizer_common.h" 23#include "sanitizer_common/sanitizer_mutex.h" 24#include "sanitizer_common/sanitizer_placement_new.h" 25 26namespace __asan { 27 28typedef __asan_global Global; 29 30struct ListOfGlobals { 31 const Global *g; 32 ListOfGlobals *next; 33}; 34 35static BlockingMutex mu_for_globals(LINKER_INITIALIZED); 36static LowLevelAllocator allocator_for_globals; 37static ListOfGlobals *list_of_all_globals; 38 39static const int kDynamicInitGlobalsInitialCapacity = 512; 40struct DynInitGlobal { 41 Global g; 42 bool initialized; 43}; 44typedef InternalVector<DynInitGlobal> VectorOfGlobals; 45// Lazy-initialized and never deleted. 46static VectorOfGlobals *dynamic_init_globals; 47 48ALWAYS_INLINE void PoisonShadowForGlobal(const Global *g, u8 value) { 49 FastPoisonShadow(g->beg, g->size_with_redzone, value); 50} 51 52ALWAYS_INLINE void PoisonRedZones(const Global &g) { 53 uptr aligned_size = RoundUpTo(g.size, SHADOW_GRANULARITY); 54 FastPoisonShadow(g.beg + aligned_size, g.size_with_redzone - aligned_size, 55 kAsanGlobalRedzoneMagic); 56 if (g.size != aligned_size) { 57 FastPoisonShadowPartialRightRedzone( 58 g.beg + RoundDownTo(g.size, SHADOW_GRANULARITY), 59 g.size % SHADOW_GRANULARITY, 60 SHADOW_GRANULARITY, 61 kAsanGlobalRedzoneMagic); 62 } 63} 64 65static void ReportGlobal(const Global &g, const char *prefix) { 66 Report("%s Global: beg=%p size=%zu/%zu name=%s module=%s dyn_init=%zu\n", 67 prefix, (void*)g.beg, g.size, g.size_with_redzone, g.name, 68 g.module_name, g.has_dynamic_init); 69} 70 71bool DescribeAddressIfGlobal(uptr addr, uptr size) { 72 if (!flags()->report_globals) return false; 73 BlockingMutexLock lock(&mu_for_globals); 74 bool res = false; 75 for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) { 76 const Global &g = *l->g; 77 if (flags()->report_globals >= 2) 78 ReportGlobal(g, "Search"); 79 res |= DescribeAddressRelativeToGlobal(addr, size, g); 80 } 81 return res; 82} 83 84// Register a global variable. 85// This function may be called more than once for every global 86// so we store the globals in a map. 87static void RegisterGlobal(const Global *g) { 88 CHECK(asan_inited); 89 if (flags()->report_globals >= 2) 90 ReportGlobal(*g, "Added"); 91 CHECK(flags()->report_globals); 92 CHECK(AddrIsInMem(g->beg)); 93 CHECK(AddrIsAlignedByGranularity(g->beg)); 94 CHECK(AddrIsAlignedByGranularity(g->size_with_redzone)); 95 if (flags()->poison_heap) 96 PoisonRedZones(*g); 97 ListOfGlobals *l = 98 (ListOfGlobals*)allocator_for_globals.Allocate(sizeof(ListOfGlobals)); 99 l->g = g; 100 l->next = list_of_all_globals; 101 list_of_all_globals = l; 102 if (g->has_dynamic_init) { 103 if (dynamic_init_globals == 0) { 104 void *mem = allocator_for_globals.Allocate(sizeof(VectorOfGlobals)); 105 dynamic_init_globals = new(mem) 106 VectorOfGlobals(kDynamicInitGlobalsInitialCapacity); 107 } 108 DynInitGlobal dyn_global = { *g, false }; 109 dynamic_init_globals->push_back(dyn_global); 110 } 111} 112 113static void UnregisterGlobal(const Global *g) { 114 CHECK(asan_inited); 115 CHECK(flags()->report_globals); 116 CHECK(AddrIsInMem(g->beg)); 117 CHECK(AddrIsAlignedByGranularity(g->beg)); 118 CHECK(AddrIsAlignedByGranularity(g->size_with_redzone)); 119 if (flags()->poison_heap) 120 PoisonShadowForGlobal(g, 0); 121 // We unpoison the shadow memory for the global but we do not remove it from 122 // the list because that would require O(n^2) time with the current list 123 // implementation. It might not be worth doing anyway. 124} 125 126} // namespace __asan 127 128// ---------------------- Interface ---------------- {{{1 129using namespace __asan; // NOLINT 130 131// Register an array of globals. 132void __asan_register_globals(__asan_global *globals, uptr n) { 133 if (!flags()->report_globals) return; 134 BlockingMutexLock lock(&mu_for_globals); 135 for (uptr i = 0; i < n; i++) { 136 RegisterGlobal(&globals[i]); 137 } 138} 139 140// Unregister an array of globals. 141// We must do this when a shared objects gets dlclosed. 142void __asan_unregister_globals(__asan_global *globals, uptr n) { 143 if (!flags()->report_globals) return; 144 BlockingMutexLock lock(&mu_for_globals); 145 for (uptr i = 0; i < n; i++) { 146 UnregisterGlobal(&globals[i]); 147 } 148} 149 150// This method runs immediately prior to dynamic initialization in each TU, 151// when all dynamically initialized globals are unpoisoned. This method 152// poisons all global variables not defined in this TU, so that a dynamic 153// initializer can only touch global variables in the same TU. 154void __asan_before_dynamic_init(const char *module_name) { 155 if (!flags()->check_initialization_order || 156 !flags()->poison_heap) 157 return; 158 bool strict_init_order = flags()->strict_init_order; 159 CHECK(dynamic_init_globals); 160 CHECK(module_name); 161 CHECK(asan_inited); 162 BlockingMutexLock lock(&mu_for_globals); 163 if (flags()->report_globals >= 3) 164 Printf("DynInitPoison module: %s\n", module_name); 165 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 166 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 167 const Global *g = &dyn_g.g; 168 if (dyn_g.initialized) 169 continue; 170 if (g->module_name != module_name) 171 PoisonShadowForGlobal(g, kAsanInitializationOrderMagic); 172 else if (!strict_init_order) 173 dyn_g.initialized = true; 174 } 175} 176 177// This method runs immediately after dynamic initialization in each TU, when 178// all dynamically initialized globals except for those defined in the current 179// TU are poisoned. It simply unpoisons all dynamically initialized globals. 180void __asan_after_dynamic_init() { 181 if (!flags()->check_initialization_order || 182 !flags()->poison_heap) 183 return; 184 CHECK(asan_inited); 185 BlockingMutexLock lock(&mu_for_globals); 186 // FIXME: Optionally report that we're unpoisoning globals from a module. 187 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 188 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 189 const Global *g = &dyn_g.g; 190 if (!dyn_g.initialized) { 191 // Unpoison the whole global. 192 PoisonShadowForGlobal(g, 0); 193 // Poison redzones back. 194 PoisonRedZones(*g); 195 } 196 } 197} 198