asan_globals.cc revision 53177247698bfba075f2d5b255a447fc3ced6976
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 InternalMmapVector<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 = new(allocator_for_globals) ListOfGlobals; 98 l->g = g; 99 l->next = list_of_all_globals; 100 list_of_all_globals = l; 101 if (g->has_dynamic_init) { 102 if (dynamic_init_globals == 0) { 103 dynamic_init_globals = new(allocator_for_globals) 104 VectorOfGlobals(kDynamicInitGlobalsInitialCapacity); 105 } 106 DynInitGlobal dyn_global = { *g, false }; 107 dynamic_init_globals->push_back(dyn_global); 108 } 109} 110 111static void UnregisterGlobal(const Global *g) { 112 CHECK(asan_inited); 113 CHECK(flags()->report_globals); 114 CHECK(AddrIsInMem(g->beg)); 115 CHECK(AddrIsAlignedByGranularity(g->beg)); 116 CHECK(AddrIsAlignedByGranularity(g->size_with_redzone)); 117 if (flags()->poison_heap) 118 PoisonShadowForGlobal(g, 0); 119 // We unpoison the shadow memory for the global but we do not remove it from 120 // the list because that would require O(n^2) time with the current list 121 // implementation. It might not be worth doing anyway. 122} 123 124void StopInitOrderChecking() { 125 BlockingMutexLock lock(&mu_for_globals); 126 if (!flags()->check_initialization_order || !dynamic_init_globals) 127 return; 128 flags()->check_initialization_order = false; 129 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 130 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 131 const Global *g = &dyn_g.g; 132 // Unpoison the whole global. 133 PoisonShadowForGlobal(g, 0); 134 // Poison redzones back. 135 PoisonRedZones(*g); 136 } 137} 138 139} // namespace __asan 140 141// ---------------------- Interface ---------------- {{{1 142using namespace __asan; // NOLINT 143 144// Register an array of globals. 145void __asan_register_globals(__asan_global *globals, uptr n) { 146 if (!flags()->report_globals) return; 147 BlockingMutexLock lock(&mu_for_globals); 148 for (uptr i = 0; i < n; i++) { 149 RegisterGlobal(&globals[i]); 150 } 151} 152 153// Unregister an array of globals. 154// We must do this when a shared objects gets dlclosed. 155void __asan_unregister_globals(__asan_global *globals, uptr n) { 156 if (!flags()->report_globals) return; 157 BlockingMutexLock lock(&mu_for_globals); 158 for (uptr i = 0; i < n; i++) { 159 UnregisterGlobal(&globals[i]); 160 } 161} 162 163// This method runs immediately prior to dynamic initialization in each TU, 164// when all dynamically initialized globals are unpoisoned. This method 165// poisons all global variables not defined in this TU, so that a dynamic 166// initializer can only touch global variables in the same TU. 167void __asan_before_dynamic_init(const char *module_name) { 168 if (!flags()->check_initialization_order || 169 !flags()->poison_heap) 170 return; 171 bool strict_init_order = flags()->strict_init_order; 172 CHECK(dynamic_init_globals); 173 CHECK(module_name); 174 CHECK(asan_inited); 175 BlockingMutexLock lock(&mu_for_globals); 176 if (flags()->report_globals >= 3) 177 Printf("DynInitPoison module: %s\n", module_name); 178 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 179 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 180 const Global *g = &dyn_g.g; 181 if (dyn_g.initialized) 182 continue; 183 if (g->module_name != module_name) 184 PoisonShadowForGlobal(g, kAsanInitializationOrderMagic); 185 else if (!strict_init_order) 186 dyn_g.initialized = true; 187 } 188} 189 190// This method runs immediately after dynamic initialization in each TU, when 191// all dynamically initialized globals except for those defined in the current 192// TU are poisoned. It simply unpoisons all dynamically initialized globals. 193void __asan_after_dynamic_init() { 194 if (!flags()->check_initialization_order || 195 !flags()->poison_heap) 196 return; 197 CHECK(asan_inited); 198 BlockingMutexLock lock(&mu_for_globals); 199 // FIXME: Optionally report that we're unpoisoning globals from a module. 200 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 201 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 202 const Global *g = &dyn_g.g; 203 if (!dyn_g.initialized) { 204 // Unpoison the whole global. 205 PoisonShadowForGlobal(g, 0); 206 // Poison redzones back. 207 PoisonRedZones(*g); 208 } 209 } 210} 211