libsanitizer/asan/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_mapping.h"
  15 #include "asan_poisoning.h"
  16 #include "asan_report.h"
  17 #include "asan_stack.h"
  18 #include "asan_stats.h"
  19 #include "asan_thread.h"
  20 #include "sanitizer_common/sanitizer_common.h"
  21 #include "sanitizer_common/sanitizer_mutex.h"
  22 #include "sanitizer_common/sanitizer_placement_new.h"
  23 #include "sanitizer_common/sanitizer_stackdepot.h"
  24
  25 namespace __asan {
  26
  27 typedef __asan_global Global;
  28
  29 struct ListOfGlobals {
  30   const Global *g;
  31   ListOfGlobals *next;
  32 };
  33
  34 static BlockingMutex mu_for_globals(LINKER_INITIALIZED);
  35 static LowLevelAllocator allocator_for_globals;
  36 static ListOfGlobals *list_of_all_globals;
  37
  38 static const int kDynamicInitGlobalsInitialCapacity = 512;
  39 struct DynInitGlobal {
  40   Global g;
  41   bool initialized;
  42 };
  43 typedef InternalMmapVector<DynInitGlobal> VectorOfGlobals;
  44 // Lazy-initialized and never deleted.
  45 static VectorOfGlobals *dynamic_init_globals;
  46
  47 // We want to remember where a certain range of globals was registered.
  48 struct GlobalRegistrationSite {
  49   u32 stack_id;
  50   Global *g_first, *g_last;
  51 };
  52 typedef InternalMmapVector<GlobalRegistrationSite> GlobalRegistrationSiteVector;
  53 static GlobalRegistrationSiteVector *global_registration_site_vector;
  54
  55 ALWAYS_INLINE void PoisonShadowForGlobal(const Global *g, u8 value) {
  56   FastPoisonShadow(g->beg, g->size_with_redzone, value);
  57 }
  58
  59 ALWAYS_INLINE void PoisonRedZones(const Global &g) {
  60   uptr aligned_size = RoundUpTo(g.size, SHADOW_GRANULARITY);
  61   FastPoisonShadow(g.beg + aligned_size, g.size_with_redzone - aligned_size,
  62                    kAsanGlobalRedzoneMagic);
  63   if (g.size != aligned_size) {
  64     FastPoisonShadowPartialRightRedzone(
  65         g.beg + RoundDownTo(g.size, SHADOW_GRANULARITY),
  66         g.size % SHADOW_GRANULARITY,
  67         SHADOW_GRANULARITY,
  68         kAsanGlobalRedzoneMagic);
  69   }
  70 }
  71
  72 static void ReportGlobal(const Global &g, const char *prefix) {
  73   Report("%s Global[%p]: beg=%p size=%zu/%zu name=%s module=%s dyn_init=%zu\n",
  74          prefix, &g, (void *)g.beg, g.size, g.size_with_redzone, g.name,
  75          g.module_name, g.has_dynamic_init);
  76   if (g.location) {
  77     Report("  location (%p): name=%s[%p], %d %d\n", g.location,
  78            g.location->filename, g.location->filename, g.location->line_no,
  79            g.location->column_no);
  80   }
  81 }
  82
  83 bool DescribeAddressIfGlobal(uptr addr, uptr size) {
  84   if (!flags()->report_globals) return false;
  85   BlockingMutexLock lock(&mu_for_globals);
  86   bool res = false;
  87   for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
  88     const Global &g = *l->g;
  89     if (flags()->report_globals >= 2)
  90       ReportGlobal(g, "Search");
  91     res |= DescribeAddressRelativeToGlobal(addr, size, g);
  92   }
  93   return res;
  94 }
  95
  96 u32 FindRegistrationSite(const Global *g) {
  97   CHECK(global_registration_site_vector);
  98   for (uptr i = 0, n = global_registration_site_vector->size(); i < n; i++) {
  99     GlobalRegistrationSite &grs = (*global_registration_site_vector)[i];
 100     if (g >= grs.g_first && g <= grs.g_last)
 101       return grs.stack_id;
 102   }
 103   return 0;
 104 }
 105
 106 // Register a global variable.
 107 // This function may be called more than once for every global
 108 // so we store the globals in a map.
 109 static void RegisterGlobal(const Global *g) {
 110   CHECK(asan_inited);
 111   if (flags()->report_globals >= 2)
 112     ReportGlobal(*g, "Added");
 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()->detect_odr_violation) {
 118     // Try detecting ODR (One Definition Rule) violation, i.e. the situation
 119     // where two globals with the same name are defined in different modules.
 120     if (__asan_region_is_poisoned(g->beg, g->size_with_redzone)) {
 121       // This check may not be enough: if the first global is much larger
 122       // the entire redzone of the second global may be within the first global.
 123       for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
 124         if (g->beg == l->g->beg &&
 125             (flags()->detect_odr_violation >= 2 || g->size != l->g->size))
 126           ReportODRViolation(g, FindRegistrationSite(g),
 127                              l->g, FindRegistrationSite(l->g));
 128       }
 129     }
 130   }
 131   if (flags()->poison_heap)
 132     PoisonRedZones(*g);
 133   ListOfGlobals *l = new(allocator_for_globals) ListOfGlobals;
 134   l->g = g;
 135   l->next = list_of_all_globals;
 136   list_of_all_globals = l;
 137   if (g->has_dynamic_init) {
 138     if (dynamic_init_globals == 0) {
 139       dynamic_init_globals = new(allocator_for_globals)
 140           VectorOfGlobals(kDynamicInitGlobalsInitialCapacity);
 141     }
 142     DynInitGlobal dyn_global = { *g, false };
 143     dynamic_init_globals->push_back(dyn_global);
 144   }
 145 }
 146
 147 static void UnregisterGlobal(const Global *g) {
 148   CHECK(asan_inited);
 149   CHECK(flags()->report_globals);
 150   CHECK(AddrIsInMem(g->beg));
 151   CHECK(AddrIsAlignedByGranularity(g->beg));
 152   CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
 153   if (flags()->poison_heap)
 154     PoisonShadowForGlobal(g, 0);
 155   // We unpoison the shadow memory for the global but we do not remove it from
 156   // the list because that would require O(n^2) time with the current list
 157   // implementation. It might not be worth doing anyway.
 158 }
 159
 160 void StopInitOrderChecking() {
 161   BlockingMutexLock lock(&mu_for_globals);
 162   if (!flags()->check_initialization_order || !dynamic_init_globals)
 163     return;
 164   flags()->check_initialization_order = false;
 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     // Unpoison the whole global.
 169     PoisonShadowForGlobal(g, 0);
 170     // Poison redzones back.
 171     PoisonRedZones(*g);
 172   }
 173 }
 174
 175 }  // namespace __asan
 176
 177 // ---------------------- Interface ---------------- {{{1
 178 using namespace __asan;  // NOLINT
 179
 180 // Register an array of globals.
 181 void __asan_register_globals(__asan_global *globals, uptr n) {
 182   if (!flags()->report_globals) return;
 183   GET_STACK_TRACE_FATAL_HERE;
 184   u32 stack_id = StackDepotPut(stack.trace, stack.size);
 185   BlockingMutexLock lock(&mu_for_globals);
 186   if (!global_registration_site_vector)
 187     global_registration_site_vector =
 188         new(allocator_for_globals) GlobalRegistrationSiteVector(128);
 189   GlobalRegistrationSite site = {stack_id, &globals[0], &globals[n - 1]};
 190   global_registration_site_vector->push_back(site);
 191   if (flags()->report_globals >= 2) {
 192     PRINT_CURRENT_STACK();
 193     Printf("=== ID %d; %p %p\n", stack_id, &globals[0], &globals[n - 1]);
 194   }
 195   for (uptr i = 0; i < n; i++) {
 196     RegisterGlobal(&globals[i]);
 197   }
 198 }
 199
 200 // Unregister an array of globals.
 201 // We must do this when a shared objects gets dlclosed.
 202 void __asan_unregister_globals(__asan_global *globals, uptr n) {
 203   if (!flags()->report_globals) return;
 204   BlockingMutexLock lock(&mu_for_globals);
 205   for (uptr i = 0; i < n; i++) {
 206     UnregisterGlobal(&globals[i]);
 207   }
 208 }
 209
 210 // This method runs immediately prior to dynamic initialization in each TU,
 211 // when all dynamically initialized globals are unpoisoned.  This method
 212 // poisons all global variables not defined in this TU, so that a dynamic
 213 // initializer can only touch global variables in the same TU.
 214 void __asan_before_dynamic_init(const char *module_name) {
 215   if (!flags()->check_initialization_order ||
 216       !flags()->poison_heap)
 217     return;
 218   bool strict_init_order = flags()->strict_init_order;
 219   CHECK(dynamic_init_globals);
 220   CHECK(module_name);
 221   CHECK(asan_inited);
 222   BlockingMutexLock lock(&mu_for_globals);
 223   if (flags()->report_globals >= 3)
 224     Printf("DynInitPoison module: %s\n", module_name);
 225   for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) {
 226     DynInitGlobal &dyn_g = (*dynamic_init_globals)[i];
 227     const Global *g = &dyn_g.g;
 228     if (dyn_g.initialized)
 229       continue;
 230     if (g->module_name != module_name)
 231       PoisonShadowForGlobal(g, kAsanInitializationOrderMagic);
 232     else if (!strict_init_order)
 233       dyn_g.initialized = true;
 234   }
 235 }
 236
 237 // This method runs immediately after dynamic initialization in each TU, when
 238 // all dynamically initialized globals except for those defined in the current
 239 // TU are poisoned.  It simply unpoisons all dynamically initialized globals.
 240 void __asan_after_dynamic_init() {
 241   if (!flags()->check_initialization_order ||
 242       !flags()->poison_heap)
 243     return;
 244   CHECK(asan_inited);
 245   BlockingMutexLock lock(&mu_for_globals);
 246   // FIXME: Optionally report that we're unpoisoning globals from a module.
 247   for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) {
 248     DynInitGlobal &dyn_g = (*dynamic_init_globals)[i];
 249     const Global *g = &dyn_g.g;
 250     if (!dyn_g.initialized) {
 251       // Unpoison the whole global.
 252       PoisonShadowForGlobal(g, 0);
 253       // Poison redzones back.
 254       PoisonRedZones(*g);
 255     }
 256   }
 257 }