libsanitizer/lsan/lsan_common_linux.cc

   1 //=-- lsan_common_linux.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 LeakSanitizer.
   9 // Implementation of common leak checking functionality. Linux-specific code.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_common/sanitizer_platform.h"
  14 #include "lsan_common.h"
  15
  16 #if CAN_SANITIZE_LEAKS && SANITIZER_LINUX
  17 #include <link.h>
  18
  19 #include "sanitizer_common/sanitizer_common.h"
  20 #include "sanitizer_common/sanitizer_flags.h"
  21 #include "sanitizer_common/sanitizer_linux.h"
  22 #include "sanitizer_common/sanitizer_stackdepot.h"
  23
  24 namespace __lsan {
  25
  26 static const char kLinkerName[] = "ld";
  27
  28 static char linker_placeholder[sizeof(LoadedModule)] ALIGNED(64);
  29 static LoadedModule *linker = nullptr;
  30
  31 static bool IsLinker(const char* full_name) {
  32   return LibraryNameIs(full_name, kLinkerName);
  33 }
  34
  35 __attribute__((tls_model("initial-exec")))
  36 THREADLOCAL int disable_counter;
  37 bool DisabledInThisThread() { return disable_counter > 0; }
  38 void DisableInThisThread() { disable_counter++; }
  39 void EnableInThisThread() {
  40   if (disable_counter == 0) {
  41     DisableCounterUnderflow();
  42   }
  43   disable_counter--;
  44 }
  45
  46 void InitializePlatformSpecificModules() {
  47   ListOfModules modules;
  48   modules.init();
  49   for (LoadedModule &module : modules) {
  50     if (!IsLinker(module.full_name())) continue;
  51     if (linker == nullptr) {
  52       linker = reinterpret_cast<LoadedModule *>(linker_placeholder);
  53       *linker = module;
  54       module = LoadedModule();
  55     } else {
  56       VReport(1, "LeakSanitizer: Multiple modules match \"%s\". "
  57               "TLS will not be handled correctly.\n", kLinkerName);
  58       linker->clear();
  59       linker = nullptr;
  60       return;
  61     }
  62   }
  63   if (linker == nullptr) {
  64     VReport(1, "LeakSanitizer: Dynamic linker not found. "
  65                "TLS will not be handled correctly.\n");
  66   }
  67 }
  68
  69 static int ProcessGlobalRegionsCallback(struct dl_phdr_info *info, size_t size,
  70                                         void *data) {
  71   Frontier *frontier = reinterpret_cast<Frontier *>(data);
  72   for (uptr j = 0; j < info->dlpi_phnum; j++) {
  73     const ElfW(Phdr) *phdr = &(info->dlpi_phdr[j]);
  74     // We're looking for .data and .bss sections, which reside in writeable,
  75     // loadable segments.
  76     if (!(phdr->p_flags & PF_W) || (phdr->p_type != PT_LOAD) ||
  77         (phdr->p_memsz == 0))
  78       continue;
  79     uptr begin = info->dlpi_addr + phdr->p_vaddr;
  80     uptr end = begin + phdr->p_memsz;
  81     ScanGlobalRange(begin, end, frontier);
  82   }
  83   return 0;
  84 }
  85
  86 // Scans global variables for heap pointers.
  87 void ProcessGlobalRegions(Frontier *frontier) {
  88   if (!flags()->use_globals) return;
  89   dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier);
  90 }
  91
  92 LoadedModule *GetLinker() { return linker; }
  93
  94 void ProcessPlatformSpecificAllocations(Frontier *frontier) {}
  95
  96 struct DoStopTheWorldParam {
  97   StopTheWorldCallback callback;
  98   void *argument;
  99 };
 100
 101 // While calling Die() here is undefined behavior and can potentially
 102 // cause race conditions, it isn't possible to intercept exit on linux,
 103 // so we have no choice but to call Die() from the atexit handler.
 104 void HandleLeaks() {
 105   if (common_flags()->exitcode) Die();
 106 }
 107
 108 static int DoStopTheWorldCallback(struct dl_phdr_info *info, size_t size,
 109                                   void *data) {
 110   DoStopTheWorldParam *param = reinterpret_cast<DoStopTheWorldParam *>(data);
 111   StopTheWorld(param->callback, param->argument);
 112   return 1;
 113 }
 114
 115 // LSan calls dl_iterate_phdr() from the tracer task. This may deadlock: if one
 116 // of the threads is frozen while holding the libdl lock, the tracer will hang
 117 // in dl_iterate_phdr() forever.
 118 // Luckily, (a) the lock is reentrant and (b) libc can't distinguish between the
 119 // tracer task and the thread that spawned it. Thus, if we run the tracer task
 120 // while holding the libdl lock in the parent thread, we can safely reenter it
 121 // in the tracer. The solution is to run stoptheworld from a dl_iterate_phdr()
 122 // callback in the parent thread.
 123 void DoStopTheWorld(StopTheWorldCallback callback, void *argument) {
 124   DoStopTheWorldParam param = {callback, argument};
 125   dl_iterate_phdr(DoStopTheWorldCallback, &param);
 126 }
 127
 128 } // namespace __lsan
 129
 130 #endif // CAN_SANITIZE_LEAKS && SANITIZER_LINUX