asan_globals.cc revision 46efcb09dc16b91cb805abea52f3ff6081a63751
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 126void StopInitOrderChecking() { 127 BlockingMutexLock lock(&mu_for_globals); 128 if (!flags()->check_initialization_order || !dynamic_init_globals) 129 return; 130 flags()->check_initialization_order = false; 131 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 132 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 133 const Global *g = &dyn_g.g; 134 // Unpoison the whole global. 135 PoisonShadowForGlobal(g, 0); 136 // Poison redzones back. 137 PoisonRedZones(*g); 138 } 139} 140 141} // namespace __asan 142 143// ---------------------- Interface ---------------- {{{1 144using namespace __asan; // NOLINT 145 146// Register an array of globals. 147void __asan_register_globals(__asan_global *globals, uptr n) { 148 if (!flags()->report_globals) return; 149 BlockingMutexLock lock(&mu_for_globals); 150 for (uptr i = 0; i < n; i++) { 151 RegisterGlobal(&globals[i]); 152 } 153} 154 155// Unregister an array of globals. 156// We must do this when a shared objects gets dlclosed. 157void __asan_unregister_globals(__asan_global *globals, uptr n) { 158 if (!flags()->report_globals) return; 159 BlockingMutexLock lock(&mu_for_globals); 160 for (uptr i = 0; i < n; i++) { 161 UnregisterGlobal(&globals[i]); 162 } 163} 164 165// This method runs immediately prior to dynamic initialization in each TU, 166// when all dynamically initialized globals are unpoisoned. This method 167// poisons all global variables not defined in this TU, so that a dynamic 168// initializer can only touch global variables in the same TU. 169void __asan_before_dynamic_init(const char *module_name) { 170 if (!flags()->check_initialization_order || 171 !flags()->poison_heap) 172 return; 173 bool strict_init_order = flags()->strict_init_order; 174 CHECK(dynamic_init_globals); 175 CHECK(module_name); 176 CHECK(asan_inited); 177 BlockingMutexLock lock(&mu_for_globals); 178 if (flags()->report_globals >= 3) 179 Printf("DynInitPoison module: %s\n", module_name); 180 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 181 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 182 const Global *g = &dyn_g.g; 183 if (dyn_g.initialized) 184 continue; 185 if (g->module_name != module_name) 186 PoisonShadowForGlobal(g, kAsanInitializationOrderMagic); 187 else if (!strict_init_order) 188 dyn_g.initialized = true; 189 } 190} 191 192// This method runs immediately after dynamic initialization in each TU, when 193// all dynamically initialized globals except for those defined in the current 194// TU are poisoned. It simply unpoisons all dynamically initialized globals. 195void __asan_after_dynamic_init() { 196 if (!flags()->check_initialization_order || 197 !flags()->poison_heap) 198 return; 199 CHECK(asan_inited); 200 BlockingMutexLock lock(&mu_for_globals); 201 // FIXME: Optionally report that we're unpoisoning globals from a module. 202 for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) { 203 DynInitGlobal &dyn_g = (*dynamic_init_globals)[i]; 204 const Global *g = &dyn_g.g; 205 if (!dyn_g.initialized) { 206 // Unpoison the whole global. 207 PoisonShadowForGlobal(g, 0); 208 // Poison redzones back. 209 PoisonRedZones(*g); 210 } 211 } 212} 213