asan_linux.cc revision 2221f553886c37401b5d84923634ebf04bc482f1
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 39using namespace __sanitizer; // NOLINT 40 41extern "C" void* _DYNAMIC; 42 43namespace __asan { 44 45const uptr kMaxThreadStackSize = 256 * (1 << 20); // 256M 46 47void *AsanDoesNotSupportStaticLinkage() { 48 // This will fail to link with -static. 49 return &_DYNAMIC; // defined in link.h 50} 51 52void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) { 53#ifdef ANDROID 54 *pc = *sp = *bp = 0; 55#elif defined(__arm__) 56 ucontext_t *ucontext = (ucontext_t*)context; 57 *pc = ucontext->uc_mcontext.arm_pc; 58 *bp = ucontext->uc_mcontext.arm_fp; 59 *sp = ucontext->uc_mcontext.arm_sp; 60# elif defined(__x86_64__) 61 ucontext_t *ucontext = (ucontext_t*)context; 62 *pc = ucontext->uc_mcontext.gregs[REG_RIP]; 63 *bp = ucontext->uc_mcontext.gregs[REG_RBP]; 64 *sp = ucontext->uc_mcontext.gregs[REG_RSP]; 65# elif defined(__i386__) 66 ucontext_t *ucontext = (ucontext_t*)context; 67 *pc = ucontext->uc_mcontext.gregs[REG_EIP]; 68 *bp = ucontext->uc_mcontext.gregs[REG_EBP]; 69 *sp = ucontext->uc_mcontext.gregs[REG_ESP]; 70#else 71# error "Unsupported arch" 72#endif 73} 74 75bool AsanInterceptsSignal(int signum) { 76 return signum == SIGSEGV && FLAG_handle_segv; 77} 78 79void *AsanMmapSomewhereOrDie(uptr size, const char *mem_type) { 80 size = RoundUpTo(size, kPageSize); 81 void *res = internal_mmap(0, size, 82 PROT_READ | PROT_WRITE, 83 MAP_PRIVATE | MAP_ANON, -1, 0); 84 if (res == (void*)-1) { 85 OutOfMemoryMessageAndDie(mem_type, size); 86 } 87 return res; 88} 89 90void *AsanMmapFixedNoReserve(uptr fixed_addr, uptr size) { 91 return internal_mmap((void*)fixed_addr, size, 92 PROT_READ | PROT_WRITE, 93 MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE, 94 0, 0); 95} 96 97void *AsanMprotect(uptr fixed_addr, uptr size) { 98 return internal_mmap((void*)fixed_addr, size, 99 PROT_NONE, 100 MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE, 101 0, 0); 102} 103 104void AsanUnmapOrDie(void *addr, uptr size) { 105 if (!addr || !size) return; 106 int res = syscall(__NR_munmap, addr, size); 107 if (res != 0) { 108 Report("Failed to unmap\n"); 109 AsanDie(); 110 } 111} 112 113// Like getenv, but reads env directly from /proc and does not use libc. 114// This function should be called first inside __asan_init. 115const char* AsanGetEnv(const char* name) { 116 static char *environ; 117 static uptr len; 118 static bool inited; 119 if (!inited) { 120 inited = true; 121 uptr environ_size; 122 len = ReadFileToBuffer("/proc/self/environ", 123 &environ, &environ_size, 1 << 26); 124 } 125 if (!environ || len == 0) return 0; 126 uptr namelen = internal_strlen(name); 127 const char *p = environ; 128 while (*p != '\0') { // will happen at the \0\0 that terminates the buffer 129 // proc file has the format NAME=value\0NAME=value\0NAME=value\0... 130 const char* endp = 131 (char*)internal_memchr(p, '\0', len - (p - environ)); 132 if (endp == 0) // this entry isn't NUL terminated 133 return 0; 134 else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=') // Match. 135 return p + namelen + 1; // point after = 136 p = endp + 1; 137 } 138 return 0; // Not found. 139} 140 141AsanProcMaps::AsanProcMaps() { 142 proc_self_maps_buff_len_ = 143 ReadFileToBuffer("/proc/self/maps", &proc_self_maps_buff_, 144 &proc_self_maps_buff_mmaped_size_, 1 << 26); 145 CHECK(proc_self_maps_buff_len_ > 0); 146 // internal_write(2, proc_self_maps_buff_, proc_self_maps_buff_len_); 147 Reset(); 148} 149 150AsanProcMaps::~AsanProcMaps() { 151 AsanUnmapOrDie(proc_self_maps_buff_, proc_self_maps_buff_mmaped_size_); 152} 153 154void AsanProcMaps::Reset() { 155 current_ = proc_self_maps_buff_; 156} 157 158bool AsanProcMaps::Next(uptr *start, uptr *end, 159 uptr *offset, char filename[], 160 uptr filename_size) { 161 char *last = proc_self_maps_buff_ + proc_self_maps_buff_len_; 162 if (current_ >= last) return false; 163 int consumed = 0; 164 char flags[10]; 165 int major, minor; 166 uptr inode; 167 uptr dummy; 168 if (!start) start = &dummy; 169 if (!end) end = &dummy; 170 if (!offset) offset = &dummy; 171 char *next_line = (char*)internal_memchr(current_, '\n', last - current_); 172 if (next_line == 0) 173 next_line = last; 174 if (SScanf(current_, 175 "%lx-%lx %4s %lx %x:%x %ld %n", 176 start, end, flags, offset, &major, &minor, 177 &inode, &consumed) != 7) 178 return false; 179 current_ += consumed; 180 // Skip spaces. 181 while (current_ < next_line && *current_ == ' ') 182 current_++; 183 // Fill in the filename. 184 uptr i = 0; 185 while (current_ < next_line) { 186 if (filename && i < filename_size - 1) 187 filename[i++] = *current_; 188 current_++; 189 } 190 if (filename && i < filename_size) 191 filename[i] = 0; 192 current_ = next_line + 1; 193 return true; 194} 195 196// Gets the object name and the offset by walking AsanProcMaps. 197bool AsanProcMaps::GetObjectNameAndOffset(uptr addr, uptr *offset, 198 char filename[], 199 uptr filename_size) { 200 return IterateForObjectNameAndOffset(addr, offset, filename, filename_size); 201} 202 203void AsanThread::SetThreadStackTopAndBottom() { 204 if (tid() == 0) { 205 // This is the main thread. Libpthread may not be initialized yet. 206 struct rlimit rl; 207 CHECK(getrlimit(RLIMIT_STACK, &rl) == 0); 208 209 // Find the mapping that contains a stack variable. 210 AsanProcMaps proc_maps; 211 uptr start, end, offset; 212 uptr prev_end = 0; 213 while (proc_maps.Next(&start, &end, &offset, 0, 0)) { 214 if ((uptr)&rl < end) 215 break; 216 prev_end = end; 217 } 218 CHECK((uptr)&rl >= start && (uptr)&rl < end); 219 220 // Get stacksize from rlimit, but clip it so that it does not overlap 221 // with other mappings. 222 uptr stacksize = rl.rlim_cur; 223 if (stacksize > end - prev_end) 224 stacksize = end - prev_end; 225 // When running with unlimited stack size, we still want to set some limit. 226 // The unlimited stack size is caused by 'ulimit -s unlimited'. 227 // Also, for some reason, GNU make spawns subprocesses with unlimited stack. 228 if (stacksize > kMaxThreadStackSize) 229 stacksize = kMaxThreadStackSize; 230 stack_top_ = end; 231 stack_bottom_ = end - stacksize; 232 CHECK(AddrIsInStack((uptr)&rl)); 233 return; 234 } 235 pthread_attr_t attr; 236 CHECK(pthread_getattr_np(pthread_self(), &attr) == 0); 237 uptr stacksize = 0; 238 void *stackaddr = 0; 239 pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize); 240 pthread_attr_destroy(&attr); 241 242 stack_top_ = (uptr)stackaddr + stacksize; 243 stack_bottom_ = (uptr)stackaddr; 244 CHECK(stacksize < kMaxThreadStackSize); // Sanity check. 245 CHECK(AddrIsInStack((uptr)&attr)); 246} 247 248AsanLock::AsanLock(LinkerInitialized) { 249 // We assume that pthread_mutex_t initialized to all zeroes is a valid 250 // unlocked mutex. We can not use PTHREAD_MUTEX_INITIALIZER as it triggers 251 // a gcc warning: 252 // extended initializer lists only available with -std=c++0x or -std=gnu++0x 253} 254 255void AsanLock::Lock() { 256 CHECK(sizeof(pthread_mutex_t) <= sizeof(opaque_storage_)); 257 pthread_mutex_lock((pthread_mutex_t*)&opaque_storage_); 258 CHECK(!owner_); 259 owner_ = (uptr)pthread_self(); 260} 261 262void AsanLock::Unlock() { 263 CHECK(owner_ == (uptr)pthread_self()); 264 owner_ = 0; 265 pthread_mutex_unlock((pthread_mutex_t*)&opaque_storage_); 266} 267 268#ifdef __arm__ 269#define UNWIND_STOP _URC_END_OF_STACK 270#define UNWIND_CONTINUE _URC_NO_REASON 271#else 272#define UNWIND_STOP _URC_NORMAL_STOP 273#define UNWIND_CONTINUE _URC_NO_REASON 274#endif 275 276uptr Unwind_GetIP(struct _Unwind_Context *ctx) { 277#ifdef __arm__ 278 uptr val; 279 _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE, 280 15 /* r15 = PC */, _UVRSD_UINT32, &val); 281 CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed"); 282 // Clear the Thumb bit. 283 return val & ~(uptr)1; 284#else 285 return _Unwind_GetIP(ctx); 286#endif 287} 288 289_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, 290 void *param) { 291 AsanStackTrace *b = (AsanStackTrace*)param; 292 CHECK(b->size < b->max_size); 293 uptr pc = Unwind_GetIP(ctx); 294 b->trace[b->size++] = pc; 295 if (b->size == b->max_size) return UNWIND_STOP; 296 return UNWIND_CONTINUE; 297} 298 299void AsanStackTrace::GetStackTrace(uptr max_s, uptr pc, uptr bp) { 300 size = 0; 301 trace[0] = pc; 302 if ((max_s) > 1) { 303 max_size = max_s; 304#ifdef __arm__ 305 _Unwind_Backtrace(Unwind_Trace, this); 306#else 307 FastUnwindStack(pc, bp); 308#endif 309 } 310} 311 312} // namespace __asan 313 314#endif // __linux__ 315