asan_linux.cc revision 47657ce6cbac2fa93d0fd765c5d2872443b50e87 
1//===-- asan_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 AddressSanitizer, an address sanity checker.
11//
12// Linux-specific details.
13//===----------------------------------------------------------------------===//
14#ifdef __linux__
15
16#include "asan_interceptors.h"
17#include "asan_internal.h"
18#include "asan_lock.h"
19#include "asan_procmaps.h"
20#include "asan_thread.h"
21#include "sanitizer_common/sanitizer_libc.h"
22
23#include <sys/time.h>
24#include <sys/resource.h>
25#include <sys/mman.h>
26#include <sys/syscall.h>
27#include <sys/types.h>
28#include <fcntl.h>
29#include <pthread.h>
30#include <stdio.h>
31#include <unistd.h>
32#include <unwind.h>
33
34#ifndef ANDROID
35// FIXME: where to get ucontext on Android?
36#include <sys/ucontext.h>
37#endif
38
39extern "C" void* _DYNAMIC;
40
41namespace __asan {
42
43const uptr kMaxThreadStackSize = 256 * (1 << 20);  // 256M
44
45void *AsanDoesNotSupportStaticLinkage() {
46  // This will fail to link with -static.
47  return &_DYNAMIC;  // defined in link.h
48}
49
50void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
51#ifdef ANDROID
52  *pc = *sp = *bp = 0;
53#elif defined(__arm__)
54  ucontext_t *ucontext = (ucontext_t*)context;
55  *pc = ucontext->uc_mcontext.arm_pc;
56  *bp = ucontext->uc_mcontext.arm_fp;
57  *sp = ucontext->uc_mcontext.arm_sp;
58# elif defined(__x86_64__)
59  ucontext_t *ucontext = (ucontext_t*)context;
60  *pc = ucontext->uc_mcontext.gregs[REG_RIP];
61  *bp = ucontext->uc_mcontext.gregs[REG_RBP];
62  *sp = ucontext->uc_mcontext.gregs[REG_RSP];
63# elif defined(__i386__)
64  ucontext_t *ucontext = (ucontext_t*)context;
65  *pc = ucontext->uc_mcontext.gregs[REG_EIP];
66  *bp = ucontext->uc_mcontext.gregs[REG_EBP];
67  *sp = ucontext->uc_mcontext.gregs[REG_ESP];
68#else
69# error "Unsupported arch"
70#endif
71}
72
73bool AsanInterceptsSignal(int signum) {
74  return signum == SIGSEGV && FLAG_handle_segv;
75}
76
77void *AsanMmapSomewhereOrDie(uptr size, const char *mem_type) {
78  size = RoundUpTo(size, kPageSize);
79  void *res = internal_mmap(0, size,
80                            PROT_READ | PROT_WRITE,
81                            MAP_PRIVATE | MAP_ANON, -1, 0);
82  if (res == (void*)-1) {
83    OutOfMemoryMessageAndDie(mem_type, size);
84  }
85  return res;
86}
87
88void *AsanMmapFixedNoReserve(uptr fixed_addr, uptr size) {
89  return internal_mmap((void*)fixed_addr, size,
90                      PROT_READ | PROT_WRITE,
91                      MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE,
92                      0, 0);
93}
94
95void *AsanMprotect(uptr fixed_addr, uptr size) {
96  return internal_mmap((void*)fixed_addr, size,
97                       PROT_NONE,
98                       MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE,
99                       0, 0);
100}
101
102void AsanUnmapOrDie(void *addr, uptr size) {
103  if (!addr || !size) return;
104  int res = internal_munmap(addr, size);
105  if (res != 0) {
106    Report("Failed to unmap\n");
107    Die();
108  }
109}
110
111// Like getenv, but reads env directly from /proc and does not use libc.
112// This function should be called first inside __asan_init.
113const char* AsanGetEnv(const char* name) {
114  static char *environ;
115  static uptr len;
116  static bool inited;
117  if (!inited) {
118    inited = true;
119    uptr environ_size;
120    len = ReadFileToBuffer("/proc/self/environ",
121                           &environ, &environ_size, 1 << 26);
122  }
123  if (!environ || len == 0) return 0;
124  uptr namelen = internal_strlen(name);
125  const char *p = environ;
126  while (*p != '\0') {  // will happen at the \0\0 that terminates the buffer
127    // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
128    const char* endp =
129        (char*)internal_memchr(p, '\0', len - (p - environ));
130    if (endp == 0)  // this entry isn't NUL terminated
131      return 0;
132    else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
133      return p + namelen + 1;  // point after =
134    p = endp + 1;
135  }
136  return 0;  // Not found.
137}
138
139AsanProcMaps::AsanProcMaps() {
140  proc_self_maps_buff_len_ =
141      ReadFileToBuffer("/proc/self/maps", &proc_self_maps_buff_,
142                       &proc_self_maps_buff_mmaped_size_, 1 << 26);
143  CHECK(proc_self_maps_buff_len_ > 0);
144  // internal_write(2, proc_self_maps_buff_, proc_self_maps_buff_len_);
145  Reset();
146}
147
148AsanProcMaps::~AsanProcMaps() {
149  AsanUnmapOrDie(proc_self_maps_buff_, proc_self_maps_buff_mmaped_size_);
150}
151
152void AsanProcMaps::Reset() {
153  current_ = proc_self_maps_buff_;
154}
155
156bool AsanProcMaps::Next(uptr *start, uptr *end,
157                        uptr *offset, char filename[],
158                        uptr filename_size) {
159  char *last = proc_self_maps_buff_ + proc_self_maps_buff_len_;
160  if (current_ >= last) return false;
161  int consumed = 0;
162  char flags[10];
163  int major, minor;
164  uptr inode;
165  uptr dummy;
166  if (!start) start = &dummy;
167  if (!end) end = &dummy;
168  if (!offset) offset = &dummy;
169  char *next_line = (char*)internal_memchr(current_, '\n', last - current_);
170  if (next_line == 0)
171    next_line = last;
172  if (internal_sscanf(current_,
173                      "%lx-%lx %4s %lx %x:%x %ld %n",
174                      start, end, flags, offset, &major, &minor,
175                      &inode, &consumed) != 7)
176    return false;
177  current_ += consumed;
178  // Skip spaces.
179  while (current_ < next_line && *current_ == ' ')
180    current_++;
181  // Fill in the filename.
182  uptr i = 0;
183  while (current_ < next_line) {
184    if (filename && i < filename_size - 1)
185      filename[i++] = *current_;
186    current_++;
187  }
188  if (filename && i < filename_size)
189    filename[i] = 0;
190  current_ = next_line + 1;
191  return true;
192}
193
194// Gets the object name and the offset by walking AsanProcMaps.
195bool AsanProcMaps::GetObjectNameAndOffset(uptr addr, uptr *offset,
196                                          char filename[],
197                                          uptr filename_size) {
198  return IterateForObjectNameAndOffset(addr, offset, filename, filename_size);
199}
200
201void AsanThread::SetThreadStackTopAndBottom() {
202  if (tid() == 0) {
203    // This is the main thread. Libpthread may not be initialized yet.
204    struct rlimit rl;
205    CHECK(getrlimit(RLIMIT_STACK, &rl) == 0);
206
207    // Find the mapping that contains a stack variable.
208    AsanProcMaps proc_maps;
209    uptr start, end, offset;
210    uptr prev_end = 0;
211    while (proc_maps.Next(&start, &end, &offset, 0, 0)) {
212      if ((uptr)&rl < end)
213        break;
214      prev_end = end;
215    }
216    CHECK((uptr)&rl >= start && (uptr)&rl < end);
217
218    // Get stacksize from rlimit, but clip it so that it does not overlap
219    // with other mappings.
220    uptr stacksize = rl.rlim_cur;
221    if (stacksize > end - prev_end)
222      stacksize = end - prev_end;
223    // When running with unlimited stack size, we still want to set some limit.
224    // The unlimited stack size is caused by 'ulimit -s unlimited'.
225    // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
226    if (stacksize > kMaxThreadStackSize)
227      stacksize = kMaxThreadStackSize;
228    stack_top_ = end;
229    stack_bottom_ = end - stacksize;
230    CHECK(AddrIsInStack((uptr)&rl));
231    return;
232  }
233  pthread_attr_t attr;
234  CHECK(pthread_getattr_np(pthread_self(), &attr) == 0);
235  uptr stacksize = 0;
236  void *stackaddr = 0;
237  pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
238  pthread_attr_destroy(&attr);
239
240  stack_top_ = (uptr)stackaddr + stacksize;
241  stack_bottom_ = (uptr)stackaddr;
242  CHECK(stacksize < kMaxThreadStackSize);  // Sanity check.
243  CHECK(AddrIsInStack((uptr)&attr));
244}
245
246AsanLock::AsanLock(LinkerInitialized) {
247  // We assume that pthread_mutex_t initialized to all zeroes is a valid
248  // unlocked mutex. We can not use PTHREAD_MUTEX_INITIALIZER as it triggers
249  // a gcc warning:
250  // extended initializer lists only available with -std=c++0x or -std=gnu++0x
251}
252
253void AsanLock::Lock() {
254  CHECK(sizeof(pthread_mutex_t) <= sizeof(opaque_storage_));
255  pthread_mutex_lock((pthread_mutex_t*)&opaque_storage_);
256  CHECK(!owner_);
257  owner_ = (uptr)pthread_self();
258}
259
260void AsanLock::Unlock() {
261  CHECK(owner_ == (uptr)pthread_self());
262  owner_ = 0;
263  pthread_mutex_unlock((pthread_mutex_t*)&opaque_storage_);
264}
265
266#ifdef __arm__
267#define UNWIND_STOP _URC_END_OF_STACK
268#define UNWIND_CONTINUE _URC_NO_REASON
269#else
270#define UNWIND_STOP _URC_NORMAL_STOP
271#define UNWIND_CONTINUE _URC_NO_REASON
272#endif
273
274uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
275#ifdef __arm__
276  uptr val;
277  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
278      15 /* r15 = PC */, _UVRSD_UINT32, &val);
279  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
280  // Clear the Thumb bit.
281  return val & ~(uptr)1;
282#else
283  return _Unwind_GetIP(ctx);
284#endif
285}
286
287_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx,
288    void *param) {
289  AsanStackTrace *b = (AsanStackTrace*)param;
290  CHECK(b->size < b->max_size);
291  uptr pc = Unwind_GetIP(ctx);
292  b->trace[b->size++] = pc;
293  if (b->size == b->max_size) return UNWIND_STOP;
294  return UNWIND_CONTINUE;
295}
296
297void AsanStackTrace::GetStackTrace(uptr max_s, uptr pc, uptr bp) {
298  size = 0;
299  trace[0] = pc;
300  if ((max_s) > 1) {
301    max_size = max_s;
302#ifdef __arm__
303    _Unwind_Backtrace(Unwind_Trace, this);
304#else
305     FastUnwindStack(pc, bp);
306#endif
307  }
308}
309
310}  // namespace __asan
311
312#endif  // __linux__
313