442 lines
16 KiB
C++
442 lines
16 KiB
C++
//===-- asan_globals.cc ---------------------------------------------------===//
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of AddressSanitizer, an address sanity checker.
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//
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// Handle globals.
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//===----------------------------------------------------------------------===//
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#include "asan_interceptors.h"
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#include "asan_internal.h"
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#include "asan_mapping.h"
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#include "asan_poisoning.h"
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#include "asan_report.h"
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#include "asan_stack.h"
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#include "asan_stats.h"
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#include "asan_suppressions.h"
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#include "asan_thread.h"
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#include "sanitizer_common/sanitizer_common.h"
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#include "sanitizer_common/sanitizer_mutex.h"
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#include "sanitizer_common/sanitizer_placement_new.h"
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#include "sanitizer_common/sanitizer_stackdepot.h"
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#include "sanitizer_common/sanitizer_symbolizer.h"
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namespace __asan {
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typedef __asan_global Global;
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struct ListOfGlobals {
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const Global *g;
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ListOfGlobals *next;
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};
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static BlockingMutex mu_for_globals(LINKER_INITIALIZED);
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static LowLevelAllocator allocator_for_globals;
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static ListOfGlobals *list_of_all_globals;
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static const int kDynamicInitGlobalsInitialCapacity = 512;
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struct DynInitGlobal {
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Global g;
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bool initialized;
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};
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typedef InternalMmapVector<DynInitGlobal> VectorOfGlobals;
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// Lazy-initialized and never deleted.
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static VectorOfGlobals *dynamic_init_globals;
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// We want to remember where a certain range of globals was registered.
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struct GlobalRegistrationSite {
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u32 stack_id;
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Global *g_first, *g_last;
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};
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typedef InternalMmapVector<GlobalRegistrationSite> GlobalRegistrationSiteVector;
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static GlobalRegistrationSiteVector *global_registration_site_vector;
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ALWAYS_INLINE void PoisonShadowForGlobal(const Global *g, u8 value) {
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FastPoisonShadow(g->beg, g->size_with_redzone, value);
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}
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ALWAYS_INLINE void PoisonRedZones(const Global &g) {
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uptr aligned_size = RoundUpTo(g.size, SHADOW_GRANULARITY);
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FastPoisonShadow(g.beg + aligned_size, g.size_with_redzone - aligned_size,
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kAsanGlobalRedzoneMagic);
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if (g.size != aligned_size) {
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FastPoisonShadowPartialRightRedzone(
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g.beg + RoundDownTo(g.size, SHADOW_GRANULARITY),
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g.size % SHADOW_GRANULARITY,
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SHADOW_GRANULARITY,
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kAsanGlobalRedzoneMagic);
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}
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}
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const uptr kMinimalDistanceFromAnotherGlobal = 64;
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static bool IsAddressNearGlobal(uptr addr, const __asan_global &g) {
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if (addr <= g.beg - kMinimalDistanceFromAnotherGlobal) return false;
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if (addr >= g.beg + g.size_with_redzone) return false;
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return true;
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}
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static void ReportGlobal(const Global &g, const char *prefix) {
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Report("%s Global[%p]: beg=%p size=%zu/%zu name=%s module=%s dyn_init=%zu\n",
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prefix, &g, (void *)g.beg, g.size, g.size_with_redzone, g.name,
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g.module_name, g.has_dynamic_init);
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if (g.location) {
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Report(" location (%p): name=%s[%p], %d %d\n", g.location,
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g.location->filename, g.location->filename, g.location->line_no,
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g.location->column_no);
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}
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}
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static u32 FindRegistrationSite(const Global *g) {
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mu_for_globals.CheckLocked();
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CHECK(global_registration_site_vector);
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for (uptr i = 0, n = global_registration_site_vector->size(); i < n; i++) {
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GlobalRegistrationSite &grs = (*global_registration_site_vector)[i];
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if (g >= grs.g_first && g <= grs.g_last)
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return grs.stack_id;
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}
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return 0;
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}
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int GetGlobalsForAddress(uptr addr, Global *globals, u32 *reg_sites,
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int max_globals) {
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if (!flags()->report_globals) return 0;
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BlockingMutexLock lock(&mu_for_globals);
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int res = 0;
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for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
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const Global &g = *l->g;
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if (flags()->report_globals >= 2)
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ReportGlobal(g, "Search");
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if (IsAddressNearGlobal(addr, g)) {
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globals[res] = g;
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if (reg_sites)
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reg_sites[res] = FindRegistrationSite(&g);
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res++;
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if (res == max_globals) break;
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}
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}
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return res;
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}
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enum GlobalSymbolState {
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UNREGISTERED = 0,
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REGISTERED = 1
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};
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// Check ODR violation for given global G via special ODR indicator. We use
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// this method in case compiler instruments global variables through their
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// local aliases.
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static void CheckODRViolationViaIndicator(const Global *g) {
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u8 *odr_indicator = reinterpret_cast<u8 *>(g->odr_indicator);
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if (*odr_indicator == UNREGISTERED) {
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*odr_indicator = REGISTERED;
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return;
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}
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// If *odr_indicator is DEFINED, some module have already registered
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// externally visible symbol with the same name. This is an ODR violation.
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for (ListOfGlobals *l = list_of_all_globals; l; l = l->next) {
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if (g->odr_indicator == l->g->odr_indicator &&
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(flags()->detect_odr_violation >= 2 || g->size != l->g->size) &&
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!IsODRViolationSuppressed(g->name))
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ReportODRViolation(g, FindRegistrationSite(g),
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l->g, FindRegistrationSite(l->g));
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}
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}
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// Clang provides two different ways for global variables protection:
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// it can poison the global itself or its private alias. In former
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// case we may poison same symbol multiple times, that can help us to
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// cheaply detect ODR violation: if we try to poison an already poisoned
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// global, we have ODR violation error.
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// In latter case, we poison each symbol exactly once, so we use special
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// indicator symbol to perform similar check.
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// In either case, compiler provides a special odr_indicator field to Global
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// structure, that can contain two kinds of values:
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// 1) Non-zero value. In this case, odr_indicator is an address of
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// corresponding indicator variable for given global.
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// 2) Zero. This means that we don't use private aliases for global variables
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// and can freely check ODR violation with the first method.
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//
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// This routine chooses between two different methods of ODR violation
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// detection.
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static inline bool UseODRIndicator(const Global *g) {
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// Use ODR indicator method iff use_odr_indicator flag is set and
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// indicator symbol address is not 0.
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return flags()->use_odr_indicator && g->odr_indicator > 0;
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}
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// Register a global variable.
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// This function may be called more than once for every global
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// so we store the globals in a map.
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static void RegisterGlobal(const Global *g) {
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CHECK(asan_inited);
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if (flags()->report_globals >= 2)
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ReportGlobal(*g, "Added");
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CHECK(flags()->report_globals);
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CHECK(AddrIsInMem(g->beg));
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if (!AddrIsAlignedByGranularity(g->beg)) {
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Report("The following global variable is not properly aligned.\n");
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Report("This may happen if another global with the same name\n");
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Report("resides in another non-instrumented module.\n");
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Report("Or the global comes from a C file built w/o -fno-common.\n");
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Report("In either case this is likely an ODR violation bug,\n");
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Report("but AddressSanitizer can not provide more details.\n");
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ReportODRViolation(g, FindRegistrationSite(g), g, FindRegistrationSite(g));
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CHECK(AddrIsAlignedByGranularity(g->beg));
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}
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CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
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if (flags()->detect_odr_violation) {
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// Try detecting ODR (One Definition Rule) violation, i.e. the situation
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// where two globals with the same name are defined in different modules.
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if (UseODRIndicator(g))
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CheckODRViolationViaIndicator(g);
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}
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if (CanPoisonMemory())
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PoisonRedZones(*g);
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ListOfGlobals *l = new(allocator_for_globals) ListOfGlobals;
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l->g = g;
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l->next = list_of_all_globals;
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list_of_all_globals = l;
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if (g->has_dynamic_init) {
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if (!dynamic_init_globals) {
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dynamic_init_globals =
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new (allocator_for_globals) VectorOfGlobals; // NOLINT
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dynamic_init_globals->reserve(kDynamicInitGlobalsInitialCapacity);
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}
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DynInitGlobal dyn_global = { *g, false };
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dynamic_init_globals->push_back(dyn_global);
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}
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}
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static void UnregisterGlobal(const Global *g) {
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CHECK(asan_inited);
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if (flags()->report_globals >= 2)
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ReportGlobal(*g, "Removed");
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CHECK(flags()->report_globals);
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CHECK(AddrIsInMem(g->beg));
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CHECK(AddrIsAlignedByGranularity(g->beg));
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CHECK(AddrIsAlignedByGranularity(g->size_with_redzone));
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if (CanPoisonMemory())
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PoisonShadowForGlobal(g, 0);
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// We unpoison the shadow memory for the global but we do not remove it from
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// the list because that would require O(n^2) time with the current list
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// implementation. It might not be worth doing anyway.
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// Release ODR indicator.
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if (UseODRIndicator(g)) {
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u8 *odr_indicator = reinterpret_cast<u8 *>(g->odr_indicator);
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*odr_indicator = UNREGISTERED;
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}
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}
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void StopInitOrderChecking() {
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BlockingMutexLock lock(&mu_for_globals);
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if (!flags()->check_initialization_order || !dynamic_init_globals)
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return;
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flags()->check_initialization_order = false;
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for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) {
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DynInitGlobal &dyn_g = (*dynamic_init_globals)[i];
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const Global *g = &dyn_g.g;
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// Unpoison the whole global.
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PoisonShadowForGlobal(g, 0);
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// Poison redzones back.
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PoisonRedZones(*g);
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}
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}
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static bool IsASCII(unsigned char c) { return /*0x00 <= c &&*/ c <= 0x7F; }
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const char *MaybeDemangleGlobalName(const char *name) {
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// We can spoil names of globals with C linkage, so use an heuristic
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// approach to check if the name should be demangled.
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bool should_demangle = false;
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if (name[0] == '_' && name[1] == 'Z')
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should_demangle = true;
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else if (SANITIZER_WINDOWS && name[0] == '\01' && name[1] == '?')
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should_demangle = true;
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return should_demangle ? Symbolizer::GetOrInit()->Demangle(name) : name;
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}
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// Check if the global is a zero-terminated ASCII string. If so, print it.
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void PrintGlobalNameIfASCII(InternalScopedString *str, const __asan_global &g) {
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for (uptr p = g.beg; p < g.beg + g.size - 1; p++) {
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unsigned char c = *(unsigned char *)p;
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if (c == '\0' || !IsASCII(c)) return;
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}
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if (*(char *)(g.beg + g.size - 1) != '\0') return;
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str->append(" '%s' is ascii string '%s'\n", MaybeDemangleGlobalName(g.name),
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(char *)g.beg);
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}
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static const char *GlobalFilename(const __asan_global &g) {
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const char *res = g.module_name;
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// Prefer the filename from source location, if is available.
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if (g.location) res = g.location->filename;
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CHECK(res);
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return res;
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}
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void PrintGlobalLocation(InternalScopedString *str, const __asan_global &g) {
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str->append("%s", GlobalFilename(g));
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if (!g.location) return;
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if (g.location->line_no) str->append(":%d", g.location->line_no);
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if (g.location->column_no) str->append(":%d", g.location->column_no);
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}
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} // namespace __asan
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// ---------------------- Interface ---------------- {{{1
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using namespace __asan; // NOLINT
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// Apply __asan_register_globals to all globals found in the same loaded
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// executable or shared library as `flag'. The flag tracks whether globals have
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// already been registered or not for this image.
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void __asan_register_image_globals(uptr *flag) {
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if (*flag)
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return;
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AsanApplyToGlobals(__asan_register_globals, flag);
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*flag = 1;
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}
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// This mirrors __asan_register_image_globals.
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void __asan_unregister_image_globals(uptr *flag) {
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if (!*flag)
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return;
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AsanApplyToGlobals(__asan_unregister_globals, flag);
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*flag = 0;
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}
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void __asan_register_elf_globals(uptr *flag, void *start, void *stop) {
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if (*flag) return;
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if (!start) return;
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CHECK_EQ(0, ((uptr)stop - (uptr)start) % sizeof(__asan_global));
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__asan_global *globals_start = (__asan_global*)start;
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__asan_global *globals_stop = (__asan_global*)stop;
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__asan_register_globals(globals_start, globals_stop - globals_start);
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*flag = 1;
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}
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void __asan_unregister_elf_globals(uptr *flag, void *start, void *stop) {
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if (!*flag) return;
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if (!start) return;
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CHECK_EQ(0, ((uptr)stop - (uptr)start) % sizeof(__asan_global));
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__asan_global *globals_start = (__asan_global*)start;
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__asan_global *globals_stop = (__asan_global*)stop;
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__asan_unregister_globals(globals_start, globals_stop - globals_start);
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*flag = 0;
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}
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// Register an array of globals.
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void __asan_register_globals(__asan_global *globals, uptr n) {
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if (!flags()->report_globals) return;
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GET_STACK_TRACE_MALLOC;
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u32 stack_id = StackDepotPut(stack);
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BlockingMutexLock lock(&mu_for_globals);
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if (!global_registration_site_vector) {
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global_registration_site_vector =
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new (allocator_for_globals) GlobalRegistrationSiteVector; // NOLINT
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global_registration_site_vector->reserve(128);
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}
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GlobalRegistrationSite site = {stack_id, &globals[0], &globals[n - 1]};
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global_registration_site_vector->push_back(site);
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if (flags()->report_globals >= 2) {
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PRINT_CURRENT_STACK();
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Printf("=== ID %d; %p %p\n", stack_id, &globals[0], &globals[n - 1]);
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}
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for (uptr i = 0; i < n; i++) {
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if (SANITIZER_WINDOWS && globals[i].beg == 0) {
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// The MSVC incremental linker may pad globals out to 256 bytes. As long
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// as __asan_global is less than 256 bytes large and its size is a power
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// of two, we can skip over the padding.
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static_assert(
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sizeof(__asan_global) < 256 &&
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(sizeof(__asan_global) & (sizeof(__asan_global) - 1)) == 0,
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"sizeof(__asan_global) incompatible with incremental linker padding");
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// If these are padding bytes, the rest of the global should be zero.
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CHECK(globals[i].size == 0 && globals[i].size_with_redzone == 0 &&
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globals[i].name == nullptr && globals[i].module_name == nullptr &&
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globals[i].odr_indicator == 0);
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continue;
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}
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RegisterGlobal(&globals[i]);
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}
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// Poison the metadata. It should not be accessible to user code.
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PoisonShadow(reinterpret_cast<uptr>(globals), n * sizeof(__asan_global),
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kAsanGlobalRedzoneMagic);
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}
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// Unregister an array of globals.
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// We must do this when a shared objects gets dlclosed.
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void __asan_unregister_globals(__asan_global *globals, uptr n) {
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if (!flags()->report_globals) return;
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BlockingMutexLock lock(&mu_for_globals);
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for (uptr i = 0; i < n; i++) {
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if (SANITIZER_WINDOWS && globals[i].beg == 0) {
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// Skip globals that look like padding from the MSVC incremental linker.
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// See comment in __asan_register_globals.
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continue;
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}
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UnregisterGlobal(&globals[i]);
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}
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// Unpoison the metadata.
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PoisonShadow(reinterpret_cast<uptr>(globals), n * sizeof(__asan_global), 0);
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}
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// This method runs immediately prior to dynamic initialization in each TU,
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// when all dynamically initialized globals are unpoisoned. This method
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// poisons all global variables not defined in this TU, so that a dynamic
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// initializer can only touch global variables in the same TU.
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void __asan_before_dynamic_init(const char *module_name) {
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if (!flags()->check_initialization_order ||
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!CanPoisonMemory() ||
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!dynamic_init_globals)
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return;
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bool strict_init_order = flags()->strict_init_order;
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CHECK(module_name);
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CHECK(asan_inited);
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BlockingMutexLock lock(&mu_for_globals);
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if (flags()->report_globals >= 3)
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Printf("DynInitPoison module: %s\n", module_name);
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for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) {
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DynInitGlobal &dyn_g = (*dynamic_init_globals)[i];
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const Global *g = &dyn_g.g;
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if (dyn_g.initialized)
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continue;
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if (g->module_name != module_name)
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PoisonShadowForGlobal(g, kAsanInitializationOrderMagic);
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else if (!strict_init_order)
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dyn_g.initialized = true;
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}
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}
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// This method runs immediately after dynamic initialization in each TU, when
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// all dynamically initialized globals except for those defined in the current
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// TU are poisoned. It simply unpoisons all dynamically initialized globals.
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void __asan_after_dynamic_init() {
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if (!flags()->check_initialization_order ||
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!CanPoisonMemory() ||
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!dynamic_init_globals)
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return;
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CHECK(asan_inited);
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BlockingMutexLock lock(&mu_for_globals);
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// FIXME: Optionally report that we're unpoisoning globals from a module.
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for (uptr i = 0, n = dynamic_init_globals->size(); i < n; ++i) {
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DynInitGlobal &dyn_g = (*dynamic_init_globals)[i];
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const Global *g = &dyn_g.g;
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if (!dyn_g.initialized) {
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// Unpoison the whole global.
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PoisonShadowForGlobal(g, 0);
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// Poison redzones back.
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PoisonRedZones(*g);
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}
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}
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}
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