lsan_common_linux.cc revision 2946f13d6ca0cfc46d74c12e97dc40a17a7d232f 
1//=-- lsan_common_linux.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 LeakSanitizer.
11// Implementation of common leak checking functionality. Linux-specific code.
12//
13//===----------------------------------------------------------------------===//
14
15#include "sanitizer_common/sanitizer_platform.h"
16#include "lsan_common.h"
17
18#if CAN_SANITIZE_LEAKS && SANITIZER_LINUX
19#include <link.h>
20
21#include "sanitizer_common/sanitizer_common.h"
22#include "sanitizer_common/sanitizer_linux.h"
23#include "sanitizer_common/sanitizer_stackdepot.h"
24
25namespace __lsan {
26
27static const char kLinkerName[] = "ld";
28// We request 2 modules matching "ld", so we can print a warning if there's more
29// than one match. But only the first one is actually used.
30static char linker_placeholder[2 * sizeof(LoadedModule)] ALIGNED(64);
31static LoadedModule *linker = 0;
32
33static bool IsLinker(const char* full_name) {
34  return LibraryNameIs(full_name, kLinkerName);
35}
36
37void InitializePlatformSpecificModules() {
38  internal_memset(linker_placeholder, 0, sizeof(linker_placeholder));
39  uptr num_matches = GetListOfModules(
40      reinterpret_cast<LoadedModule *>(linker_placeholder), 2, IsLinker);
41  if (num_matches == 1) {
42    linker = reinterpret_cast<LoadedModule *>(linker_placeholder);
43    return;
44  }
45  if (num_matches == 0)
46    Report("LeakSanitizer: Dynamic linker not found. "
47           "TLS will not be handled correctly.\n");
48  else if (num_matches > 1)
49    Report("LeakSanitizer: Multiple modules match \"%s\". "
50           "TLS will not be handled correctly.\n", kLinkerName);
51  linker = 0;
52}
53
54static int ProcessGlobalRegionsCallback(struct dl_phdr_info *info, size_t size,
55                                        void *data) {
56  Frontier *frontier = reinterpret_cast<Frontier *>(data);
57  for (uptr j = 0; j < info->dlpi_phnum; j++) {
58    const ElfW(Phdr) *phdr = &(info->dlpi_phdr[j]);
59    // We're looking for .data and .bss sections, which reside in writeable,
60    // loadable segments.
61    if (!(phdr->p_flags & PF_W) || (phdr->p_type != PT_LOAD) ||
62        (phdr->p_memsz == 0))
63      continue;
64    uptr begin = info->dlpi_addr + phdr->p_vaddr;
65    uptr end = begin + phdr->p_memsz;
66    uptr allocator_begin = 0, allocator_end = 0;
67    GetAllocatorGlobalRange(&allocator_begin, &allocator_end);
68    if (begin <= allocator_begin && allocator_begin < end) {
69      CHECK_LE(allocator_begin, allocator_end);
70      CHECK_LT(allocator_end, end);
71      if (begin < allocator_begin)
72        ScanRangeForPointers(begin, allocator_begin, frontier, "GLOBAL",
73                             kReachable);
74      if (allocator_end < end)
75        ScanRangeForPointers(allocator_end, end, frontier, "GLOBAL",
76                             kReachable);
77    } else {
78      ScanRangeForPointers(begin, end, frontier, "GLOBAL", kReachable);
79    }
80  }
81  return 0;
82}
83
84// Scans global variables for heap pointers.
85void ProcessGlobalRegions(Frontier *frontier) {
86  // FIXME: dl_iterate_phdr acquires a linker lock, so we run a risk of
87  // deadlocking by running this under StopTheWorld. However, the lock is
88  // reentrant, so we should be able to fix this by acquiring the lock before
89  // suspending threads.
90  dl_iterate_phdr(ProcessGlobalRegionsCallback, frontier);
91}
92
93static uptr GetCallerPC(u32 stack_id, StackDepotReverseMap *map) {
94  CHECK(stack_id);
95  uptr size = 0;
96  const uptr *trace = map->Get(stack_id, &size);
97  // The top frame is our malloc/calloc/etc. The next frame is the caller.
98  if (size >= 2)
99    return trace[1];
100  return 0;
101}
102
103struct ProcessPlatformAllocParam {
104  Frontier *frontier;
105  StackDepotReverseMap *stack_depot_reverse_map;
106};
107
108// ForEachChunk callback. Identifies unreachable chunks which must be treated as
109// reachable. Marks them as reachable and adds them to the frontier.
110static void ProcessPlatformSpecificAllocationsCb(uptr chunk, void *arg) {
111  CHECK(arg);
112  ProcessPlatformAllocParam *param =
113      reinterpret_cast<ProcessPlatformAllocParam *>(arg);
114  chunk = GetUserBegin(chunk);
115  LsanMetadata m(chunk);
116  if (m.allocated() && m.tag() != kReachable) {
117    u32 stack_id = m.stack_trace_id();
118    uptr caller_pc = 0;
119    if (stack_id > 0)
120      caller_pc = GetCallerPC(stack_id, param->stack_depot_reverse_map);
121    // If caller_pc is unknown, this chunk may be allocated in a coroutine. Mark
122    // it as reachable, as we can't properly report its allocation stack anyway.
123    if (caller_pc == 0 || linker->containsAddress(caller_pc)) {
124      m.set_tag(kReachable);
125      param->frontier->push_back(chunk);
126    }
127  }
128}
129
130// Handles dynamically allocated TLS blocks by treating all chunks allocated
131// from ld-linux.so as reachable.
132void ProcessPlatformSpecificAllocations(Frontier *frontier) {
133  if (!flags()->use_tls) return;
134  if (!linker) return;
135  StackDepotReverseMap stack_depot_reverse_map;
136  ProcessPlatformAllocParam arg = {frontier, &stack_depot_reverse_map};
137  ForEachChunk(ProcessPlatformSpecificAllocationsCb, &arg);
138}
139
140}  // namespace __lsan
141#endif  // CAN_SANITIZE_LEAKS && SANITIZER_LINUX
142