libasan/asan_globals.cc

   1 //===-- asan_globals.cc ---------------------------------------------------===//
   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 // Handle globals.
  11 //===----------------------------------------------------------------------===//
  12 #include "asan_interceptors.h"
  13 #include "asan_internal.h"
  14 #include "asan_lock.h"
  15 #include "asan_mapping.h"
  16 #include "asan_report.h"
  17 #include "asan_stack.h"
  18 #include "asan_stats.h"
  19 #include "asan_thread.h"
  20 #include "sanitizer/asan_interface.h"
  21
  22 namespace __asan {
  23
  24 typedef __asan_global Global;
  25
  26 struct ListOfGlobals {
  27   const Global *g;
  28   ListOfGlobals *next;
  29 };
  30
  31 static AsanLock mu_for_globals(LINKER_INITIALIZED);
  32 static LowLevelAllocator allocator_for_globals;
  33 static ListOfGlobals *list_of_all_globals;
  34 static ListOfGlobals *list_of_dynamic_init_globals;
  35
  36 void PoisonRedZones(const Global &g)  {
  37   uptr shadow_rz_size = kGlobalAndStackRedzone >> SHADOW_SCALE;
  38   CHECK(shadow_rz_size == 1 || shadow_rz_size == 2 || shadow_rz_size == 4);
  39   // full right redzone
  40   uptr g_aligned_size = kGlobalAndStackRedzone *
  41       ((g.size + kGlobalAndStackRedzone - 1) / kGlobalAndStackRedzone);
  42   PoisonShadow(g.beg + g_aligned_size,
  43                kGlobalAndStackRedzone, kAsanGlobalRedzoneMagic);
  44   if ((g.size % kGlobalAndStackRedzone) != 0) {
  45     // partial right redzone
  46     u64 g_aligned_down_size = kGlobalAndStackRedzone *
  47         (g.size / kGlobalAndStackRedzone);
  48     CHECK(g_aligned_down_size == g_aligned_size - kGlobalAndStackRedzone);
  49     PoisonShadowPartialRightRedzone(g.beg + g_aligned_down_size,
  50                                     g.size % kGlobalAndStackRedzone,
  51                                     kGlobalAndStackRedzone,
  52                                     kAsanGlobalRedzoneMagic);
  53   }
  54 }
  55
  56 static uptr GetAlignedSize(uptr size) {
  57   return ((size + kGlobalAndStackRedzone - 1) / kGlobalAndStackRedzone)
  58       * kGlobalAndStackRedzone;
  59 }
  60
  61 bool DescribeAddressIfGlobal(uptr addr) {
  62   if (!flags()->report_globals) return false;
  63   ScopedLock lock(&mu_for_globals);
  64   bool res = false;
  65   for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
  66     const Global &g = *l->g;
  67     if (flags()->report_globals >= 2)
  68       Report("Search Global: beg=%p size=%zu name=%s\n",
  69              (void*)g.beg, g.size, (char*)g.name);
  70     res |= DescribeAddressRelativeToGlobal(addr, g);
  71   }
  72   return res;
  73 }
  74
  75 // Register a global variable.
  76 // This function may be called more than once for every global
  77 // so we store the globals in a map.
  78 static void RegisterGlobal(const Global *g) {
  79   CHECK(asan_inited);
  80   if (flags()->report_globals >= 2)
  81     Report("Added Global: beg=%p size=%zu/%zu name=%s dyn.init=%zu\n",
  82            (void*)g->beg, g->size, g->size_with_redzone, g->name,
  83            g->has_dynamic_init);
  84   CHECK(flags()->report_globals);
  85   CHECK(AddrIsInMem(g->beg));
  86   CHECK(AddrIsAlignedByGranularity(g->beg));
  87   CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
  88   PoisonRedZones(*g);
  89   ListOfGlobals *l =
  90       (ListOfGlobals*)allocator_for_globals.Allocate(sizeof(ListOfGlobals));
  91   l->g = g;
  92   l->next = list_of_all_globals;
  93   list_of_all_globals = l;
  94   if (g->has_dynamic_init) {
  95     l = (ListOfGlobals*)allocator_for_globals.Allocate(sizeof(ListOfGlobals));
  96     l->g = g;
  97     l->next = list_of_dynamic_init_globals;
  98     list_of_dynamic_init_globals = l;
  99   }
 100 }
 101
 102 static void UnregisterGlobal(const Global *g) {
 103   CHECK(asan_inited);
 104   CHECK(flags()->report_globals);
 105   CHECK(AddrIsInMem(g->beg));
 106   CHECK(AddrIsAlignedByGranularity(g->beg));
 107   CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
 108   PoisonShadow(g->beg, g->size_with_redzone, 0);
 109   // We unpoison the shadow memory for the global but we do not remove it from
 110   // the list because that would require O(n^2) time with the current list
 111   // implementation. It might not be worth doing anyway.
 112 }
 113
 114 // Poison all shadow memory for a single global.
 115 static void PoisonGlobalAndRedzones(const Global *g) {
 116   CHECK(asan_inited);
 117   CHECK(flags()->check_initialization_order);
 118   CHECK(AddrIsInMem(g->beg));
 119   CHECK(AddrIsAlignedByGranularity(g->beg));
 120   CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
 121   if (flags()->report_globals >= 3)
 122     Printf("DynInitPoison  : %s\n", g->name);
 123   PoisonShadow(g->beg, g->size_with_redzone, kAsanInitializationOrderMagic);
 124 }
 125
 126 static void UnpoisonGlobal(const Global *g) {
 127   CHECK(asan_inited);
 128   CHECK(flags()->check_initialization_order);
 129   CHECK(AddrIsInMem(g->beg));
 130   CHECK(AddrIsAlignedByGranularity(g->beg));
 131   CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
 132   if (flags()->report_globals >= 3)
 133     Printf("DynInitUnpoison: %s\n", g->name);
 134   PoisonShadow(g->beg, g->size_with_redzone, 0);
 135   PoisonRedZones(*g);
 136 }
 137
 138 }  // namespace __asan
 139
 140 // ---------------------- Interface ---------------- {{{1
 141 using namespace __asan;  // NOLINT
 142
 143 // Register one global with a default redzone.
 144 void __asan_register_global(uptr addr, uptr size,
 145                             const char *name) {
 146   if (!flags()->report_globals) return;
 147   ScopedLock lock(&mu_for_globals);
 148   Global *g = (Global *)allocator_for_globals.Allocate(sizeof(Global));
 149   g->beg = addr;
 150   g->size = size;
 151   g->size_with_redzone = GetAlignedSize(size) + kGlobalAndStackRedzone;
 152   g->name = name;
 153   RegisterGlobal(g);
 154 }
 155
 156 // Register an array of globals.
 157 void __asan_register_globals(__asan_global *globals, uptr n) {
 158   if (!flags()->report_globals) return;
 159   ScopedLock lock(&mu_for_globals);
 160   for (uptr i = 0; i < n; i++) {
 161     RegisterGlobal(&globals[i]);
 162   }
 163 }
 164
 165 // Unregister an array of globals.
 166 // We must do this when a shared objects gets dlclosed.
 167 void __asan_unregister_globals(__asan_global *globals, uptr n) {
 168   if (!flags()->report_globals) return;
 169   ScopedLock lock(&mu_for_globals);
 170   for (uptr i = 0; i < n; i++) {
 171     UnregisterGlobal(&globals[i]);
 172   }
 173 }
 174
 175 // This method runs immediately prior to dynamic initialization in each TU,
 176 // when all dynamically initialized globals are unpoisoned.  This method
 177 // poisons all global variables not defined in this TU, so that a dynamic
 178 // initializer can only touch global variables in the same TU.
 179 void __asan_before_dynamic_init(uptr first_addr, uptr last_addr) {
 180   if (!flags()->check_initialization_order) return;
 181   CHECK(list_of_dynamic_init_globals);
 182   ScopedLock lock(&mu_for_globals);
 183   bool from_current_tu = false;
 184   // The list looks like:
 185   // a => ... => b => last_addr => ... => first_addr => c => ...
 186   // The globals of the current TU reside between last_addr and first_addr.
 187   for (ListOfGlobals *l = list_of_dynamic_init_globals; l; l = l->next) {
 188     if (l->g->beg == last_addr)
 189       from_current_tu = true;
 190     if (!from_current_tu)
 191       PoisonGlobalAndRedzones(l->g);
 192     if (l->g->beg == first_addr)
 193       from_current_tu = false;
 194   }
 195   CHECK(!from_current_tu);
 196 }
 197
 198 // This method runs immediately after dynamic initialization in each TU, when
 199 // all dynamically initialized globals except for those defined in the current
 200 // TU are poisoned.  It simply unpoisons all dynamically initialized globals.
 201 void __asan_after_dynamic_init() {
 202   if (!flags()->check_initialization_order) return;
 203   ScopedLock lock(&mu_for_globals);
 204   for (ListOfGlobals *l = list_of_dynamic_init_globals; l; l = l->next)
 205     UnpoisonGlobal(l->g);
 206 }