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
25 namespace __lsan {
26
27 static 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.
30 static char linker_placeholder[2 * sizeof(LoadedModule)] ALIGNED(64);
31 static LoadedModule *linker = 0;
32
IsLinker(const char * full_name)33 static bool IsLinker(const char* full_name) {
34 return LibraryNameIs(full_name, kLinkerName);
35 }
36
InitializePlatformSpecificModules()37 void 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
ProcessGlobalRegionsCallback(struct dl_phdr_info * info,size_t size,void * data)54 static 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.
ProcessGlobalRegions(Frontier * frontier)85 void 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
GetCallerPC(u32 stack_id)93 static uptr GetCallerPC(u32 stack_id) {
94 CHECK(stack_id);
95 uptr size = 0;
96 const uptr *trace = StackDepotGet(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
103 // ForEachChunk callback. Identifies unreachable chunks which must be treated as
104 // reachable. Marks them as reachable and adds them to the frontier.
ProcessPlatformSpecificAllocationsCb(uptr chunk,void * arg)105 static void ProcessPlatformSpecificAllocationsCb(uptr chunk, void *arg) {
106 CHECK(arg);
107 chunk = GetUserBegin(chunk);
108 LsanMetadata m(chunk);
109 if (m.allocated() && m.tag() != kReachable) {
110 if (linker->containsAddress(GetCallerPC(m.stack_trace_id()))) {
111 m.set_tag(kReachable);
112 reinterpret_cast<Frontier *>(arg)->push_back(chunk);
113 }
114 }
115 }
116
117 // Handles dynamically allocated TLS blocks by treating all chunks allocated
118 // from ld-linux.so as reachable.
ProcessPlatformSpecificAllocations(Frontier * frontier)119 void ProcessPlatformSpecificAllocations(Frontier *frontier) {
120 if (!flags()->use_tls) return;
121 if (!linker) return;
122 ForEachChunk(ProcessPlatformSpecificAllocationsCb, frontier);
123 }
124
125 } // namespace __lsan
126 #endif // CAN_SANITIZE_LEAKS && SANITIZER_LINUX
127