libsanitizer/asan/asan_poisoning.cc

   1 //===-- asan_poisoning.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 AddressSanitizer, an address sanity checker.
   9 //
  10 // Shadow memory poisoning by ASan RTL and by user application.
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "asan_poisoning.h"
  14 #include "asan_report.h"
  15 #include "asan_stack.h"
  16 #include "sanitizer_common/sanitizer_atomic.h"
  17 #include "sanitizer_common/sanitizer_libc.h"
  18 #include "sanitizer_common/sanitizer_flags.h"
  19
  20 namespace __asan {
  21
  22 static atomic_uint8_t can_poison_memory;
  23
  24 void SetCanPoisonMemory(bool value) {
  25   atomic_store(&can_poison_memory, value, memory_order_release);
  26 }
  27
  28 bool CanPoisonMemory() {
  29   return atomic_load(&can_poison_memory, memory_order_acquire);
  30 }
  31
  32 void PoisonShadow(uptr addr, uptr size, u8 value) {
  33   if (value && !CanPoisonMemory()) return;
  34   CHECK(AddrIsAlignedByGranularity(addr));
  35   CHECK(AddrIsInMem(addr));
  36   CHECK(AddrIsAlignedByGranularity(addr + size));
  37   CHECK(AddrIsInMem(addr + size - SHADOW_GRANULARITY));
  38   CHECK(REAL(memset));
  39   FastPoisonShadow(addr, size, value);
  40 }
  41
  42 void PoisonShadowPartialRightRedzone(uptr addr,
  43                                      uptr size,
  44                                      uptr redzone_size,
  45                                      u8 value) {
  46   if (!CanPoisonMemory()) return;
  47   CHECK(AddrIsAlignedByGranularity(addr));
  48   CHECK(AddrIsInMem(addr));
  49   FastPoisonShadowPartialRightRedzone(addr, size, redzone_size, value);
  50 }
  51
  52 struct ShadowSegmentEndpoint {
  53   u8 *chunk;
  54   s8 offset;  // in [0, SHADOW_GRANULARITY)
  55   s8 value;  // = *chunk;
  56
  57   explicit ShadowSegmentEndpoint(uptr address) {
  58     chunk = (u8*)MemToShadow(address);
  59     offset = address & (SHADOW_GRANULARITY - 1);
  60     value = *chunk;
  61   }
  62 };
  63
  64 void FlushUnneededASanShadowMemory(uptr p, uptr size) {
  65   // Since asan's mapping is compacting, the shadow chunk may be
  66   // not page-aligned, so we only flush the page-aligned portion.
  67   ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
  68 }
  69
  70 void AsanPoisonOrUnpoisonIntraObjectRedzone(uptr ptr, uptr size, bool poison) {
  71   uptr end = ptr + size;
  72   if (Verbosity()) {
  73     Printf("__asan_%spoison_intra_object_redzone [%p,%p) %zd\n",
  74            poison ? "" : "un", ptr, end, size);
  75     if (Verbosity() >= 2)
  76       PRINT_CURRENT_STACK();
  77   }
  78   CHECK(size);
  79   CHECK_LE(size, 4096);
  80   CHECK(IsAligned(end, SHADOW_GRANULARITY));
  81   if (!IsAligned(ptr, SHADOW_GRANULARITY)) {
  82     *(u8 *)MemToShadow(ptr) =
  83         poison ? static_cast<u8>(ptr % SHADOW_GRANULARITY) : 0;
  84     ptr |= SHADOW_GRANULARITY - 1;
  85     ptr++;
  86   }
  87   for (; ptr < end; ptr += SHADOW_GRANULARITY)
  88     *(u8*)MemToShadow(ptr) = poison ? kAsanIntraObjectRedzone : 0;
  89 }
  90
  91 }  // namespace __asan
  92
  93 // ---------------------- Interface ---------------- {{{1
  94 using namespace __asan;  // NOLINT
  95
  96 // Current implementation of __asan_(un)poison_memory_region doesn't check
  97 // that user program (un)poisons the memory it owns. It poisons memory
  98 // conservatively, and unpoisons progressively to make sure asan shadow
  99 // mapping invariant is preserved (see detailed mapping description here:
 100 // https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm).
 101 //
 102 // * if user asks to poison region [left, right), the program poisons
 103 // at least [left, AlignDown(right)).
 104 // * if user asks to unpoison region [left, right), the program unpoisons
 105 // at most [AlignDown(left), right).
 106 void __asan_poison_memory_region(void const volatile *addr, uptr size) {
 107   if (!flags()->allow_user_poisoning || size == 0) return;
 108   uptr beg_addr = (uptr)addr;
 109   uptr end_addr = beg_addr + size;
 110   VPrintf(3, "Trying to poison memory region [%p, %p)\n", (void *)beg_addr,
 111           (void *)end_addr);
 112   ShadowSegmentEndpoint beg(beg_addr);
 113   ShadowSegmentEndpoint end(end_addr);
 114   if (beg.chunk == end.chunk) {
 115     CHECK_LT(beg.offset, end.offset);
 116     s8 value = beg.value;
 117     CHECK_EQ(value, end.value);
 118     // We can only poison memory if the byte in end.offset is unaddressable.
 119     // No need to re-poison memory if it is poisoned already.
 120     if (value > 0 && value <= end.offset) {
 121       if (beg.offset > 0) {
 122         *beg.chunk = Min(value, beg.offset);
 123       } else {
 124         *beg.chunk = kAsanUserPoisonedMemoryMagic;
 125       }
 126     }
 127     return;
 128   }
 129   CHECK_LT(beg.chunk, end.chunk);
 130   if (beg.offset > 0) {
 131     // Mark bytes from beg.offset as unaddressable.
 132     if (beg.value == 0) {
 133       *beg.chunk = beg.offset;
 134     } else {
 135       *beg.chunk = Min(beg.value, beg.offset);
 136     }
 137     beg.chunk++;
 138   }
 139   REAL(memset)(beg.chunk, kAsanUserPoisonedMemoryMagic, end.chunk - beg.chunk);
 140   // Poison if byte in end.offset is unaddressable.
 141   if (end.value > 0 && end.value <= end.offset) {
 142     *end.chunk = kAsanUserPoisonedMemoryMagic;
 143   }
 144 }
 145
 146 void __asan_unpoison_memory_region(void const volatile *addr, uptr size) {
 147   if (!flags()->allow_user_poisoning || size == 0) return;
 148   uptr beg_addr = (uptr)addr;
 149   uptr end_addr = beg_addr + size;
 150   VPrintf(3, "Trying to unpoison memory region [%p, %p)\n", (void *)beg_addr,
 151           (void *)end_addr);
 152   ShadowSegmentEndpoint beg(beg_addr);
 153   ShadowSegmentEndpoint end(end_addr);
 154   if (beg.chunk == end.chunk) {
 155     CHECK_LT(beg.offset, end.offset);
 156     s8 value = beg.value;
 157     CHECK_EQ(value, end.value);
 158     // We unpoison memory bytes up to enbytes up to end.offset if it is not
 159     // unpoisoned already.
 160     if (value != 0) {
 161       *beg.chunk = Max(value, end.offset);
 162     }
 163     return;
 164   }
 165   CHECK_LT(beg.chunk, end.chunk);
 166   if (beg.offset > 0) {
 167     *beg.chunk = 0;
 168     beg.chunk++;
 169   }
 170   REAL(memset)(beg.chunk, 0, end.chunk - beg.chunk);
 171   if (end.offset > 0 && end.value != 0) {
 172     *end.chunk = Max(end.value, end.offset);
 173   }
 174 }
 175
 176 int __asan_address_is_poisoned(void const volatile *addr) {
 177   return __asan::AddressIsPoisoned((uptr)addr);
 178 }
 179
 180 uptr __asan_region_is_poisoned(uptr beg, uptr size) {
 181   if (!size) return 0;
 182   uptr end = beg + size;
 183   if (SANITIZER_MYRIAD2) {
 184     // On Myriad, address not in DRAM range need to be treated as
 185     // unpoisoned.
 186     if (!AddrIsInMem(beg) && !AddrIsInShadow(beg)) return 0;
 187     if (!AddrIsInMem(end) && !AddrIsInShadow(end)) return 0;
 188   } else {
 189     if (!AddrIsInMem(beg)) return beg;
 190     if (!AddrIsInMem(end)) return end;
 191   }
 192   CHECK_LT(beg, end);
 193   uptr aligned_b = RoundUpTo(beg, SHADOW_GRANULARITY);
 194   uptr aligned_e = RoundDownTo(end, SHADOW_GRANULARITY);
 195   uptr shadow_beg = MemToShadow(aligned_b);
 196   uptr shadow_end = MemToShadow(aligned_e);
 197   // First check the first and the last application bytes,
 198   // then check the SHADOW_GRANULARITY-aligned region by calling
 199   // mem_is_zero on the corresponding shadow.
 200   if (!__asan::AddressIsPoisoned(beg) &&
 201       !__asan::AddressIsPoisoned(end - 1) &&
 202       (shadow_end <= shadow_beg ||
 203        __sanitizer::mem_is_zero((const char *)shadow_beg,
 204                                 shadow_end - shadow_beg)))
 205     return 0;
 206   // The fast check failed, so we have a poisoned byte somewhere.
 207   // Find it slowly.
 208   for (; beg < end; beg++)
 209     if (__asan::AddressIsPoisoned(beg))
 210       return beg;
 211   UNREACHABLE("mem_is_zero returned false, but poisoned byte was not found");
 212   return 0;
 213 }
 214
 215 #define CHECK_SMALL_REGION(p, size, isWrite)                  \
 216   do {                                                        \
 217     uptr __p = reinterpret_cast<uptr>(p);                     \
 218     uptr __size = size;                                       \
 219     if (UNLIKELY(__asan::AddressIsPoisoned(__p) ||            \
 220         __asan::AddressIsPoisoned(__p + __size - 1))) {       \
 221       GET_CURRENT_PC_BP_SP;                                   \
 222       uptr __bad = __asan_region_is_poisoned(__p, __size);    \
 223       __asan_report_error(pc, bp, sp, __bad, isWrite, __size, 0);\
 224     }                                                         \
 225   } while (false)
 226
 227
 228 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 229 u16 __sanitizer_unaligned_load16(const uu16 *p) {
 230   CHECK_SMALL_REGION(p, sizeof(*p), false);
 231   return *p;
 232 }
 233
 234 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 235 u32 __sanitizer_unaligned_load32(const uu32 *p) {
 236   CHECK_SMALL_REGION(p, sizeof(*p), false);
 237   return *p;
 238 }
 239
 240 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 241 u64 __sanitizer_unaligned_load64(const uu64 *p) {
 242   CHECK_SMALL_REGION(p, sizeof(*p), false);
 243   return *p;
 244 }
 245
 246 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 247 void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
 248   CHECK_SMALL_REGION(p, sizeof(*p), true);
 249   *p = x;
 250 }
 251
 252 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 253 void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
 254   CHECK_SMALL_REGION(p, sizeof(*p), true);
 255   *p = x;
 256 }
 257
 258 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 259 void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
 260   CHECK_SMALL_REGION(p, sizeof(*p), true);
 261   *p = x;
 262 }
 263
 264 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 265 void __asan_poison_cxx_array_cookie(uptr p) {
 266   if (SANITIZER_WORDSIZE != 64) return;
 267   if (!flags()->poison_array_cookie) return;
 268   uptr s = MEM_TO_SHADOW(p);
 269   *reinterpret_cast<u8*>(s) = kAsanArrayCookieMagic;
 270 }
 271
 272 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 273 uptr __asan_load_cxx_array_cookie(uptr *p) {
 274   if (SANITIZER_WORDSIZE != 64) return *p;
 275   if (!flags()->poison_array_cookie) return *p;
 276   uptr s = MEM_TO_SHADOW(reinterpret_cast<uptr>(p));
 277   u8 sval = *reinterpret_cast<u8*>(s);
 278   if (sval == kAsanArrayCookieMagic) return *p;
 279   // If sval is not kAsanArrayCookieMagic it can only be freed memory,
 280   // which means that we are going to get double-free. So, return 0 to avoid
 281   // infinite loop of destructors. We don't want to report a double-free here
 282   // though, so print a warning just in case.
 283   // CHECK_EQ(sval, kAsanHeapFreeMagic);
 284   if (sval == kAsanHeapFreeMagic) {
 285     Report("AddressSanitizer: loaded array cookie from free-d memory; "
 286            "expect a double-free report\n");
 287     return 0;
 288   }
 289   // The cookie may remain unpoisoned if e.g. it comes from a custom
 290   // operator new defined inside a class.
 291   return *p;
 292 }
 293
 294 // This is a simplified version of __asan_(un)poison_memory_region, which
 295 // assumes that left border of region to be poisoned is properly aligned.
 296 static void PoisonAlignedStackMemory(uptr addr, uptr size, bool do_poison) {
 297   if (size == 0) return;
 298   uptr aligned_size = size & ~(SHADOW_GRANULARITY - 1);
 299   PoisonShadow(addr, aligned_size,
 300                do_poison ? kAsanStackUseAfterScopeMagic : 0);
 301   if (size == aligned_size)
 302     return;
 303   s8 end_offset = (s8)(size - aligned_size);
 304   s8* shadow_end = (s8*)MemToShadow(addr + aligned_size);
 305   s8 end_value = *shadow_end;
 306   if (do_poison) {
 307     // If possible, mark all the bytes mapping to last shadow byte as
 308     // unaddressable.
 309     if (end_value > 0 && end_value <= end_offset)
 310       *shadow_end = (s8)kAsanStackUseAfterScopeMagic;
 311   } else {
 312     // If necessary, mark few first bytes mapping to last shadow byte
 313     // as addressable
 314     if (end_value != 0)
 315       *shadow_end = Max(end_value, end_offset);
 316   }
 317 }
 318
 319 void __asan_set_shadow_00(uptr addr, uptr size) {
 320   REAL(memset)((void *)addr, 0, size);
 321 }
 322
 323 void __asan_set_shadow_f1(uptr addr, uptr size) {
 324   REAL(memset)((void *)addr, 0xf1, size);
 325 }
 326
 327 void __asan_set_shadow_f2(uptr addr, uptr size) {
 328   REAL(memset)((void *)addr, 0xf2, size);
 329 }
 330
 331 void __asan_set_shadow_f3(uptr addr, uptr size) {
 332   REAL(memset)((void *)addr, 0xf3, size);
 333 }
 334
 335 void __asan_set_shadow_f5(uptr addr, uptr size) {
 336   REAL(memset)((void *)addr, 0xf5, size);
 337 }
 338
 339 void __asan_set_shadow_f8(uptr addr, uptr size) {
 340   REAL(memset)((void *)addr, 0xf8, size);
 341 }
 342
 343 void __asan_poison_stack_memory(uptr addr, uptr size) {
 344   VReport(1, "poisoning: %p %zx\n", (void *)addr, size);
 345   PoisonAlignedStackMemory(addr, size, true);
 346 }
 347
 348 void __asan_unpoison_stack_memory(uptr addr, uptr size) {
 349   VReport(1, "unpoisoning: %p %zx\n", (void *)addr, size);
 350   PoisonAlignedStackMemory(addr, size, false);
 351 }
 352
 353 void __sanitizer_annotate_contiguous_container(const void *beg_p,
 354                                                const void *end_p,
 355                                                const void *old_mid_p,
 356                                                const void *new_mid_p) {
 357   if (!flags()->detect_container_overflow) return;
 358   VPrintf(2, "contiguous_container: %p %p %p %p\n", beg_p, end_p, old_mid_p,
 359           new_mid_p);
 360   uptr beg = reinterpret_cast<uptr>(beg_p);
 361   uptr end = reinterpret_cast<uptr>(end_p);
 362   uptr old_mid = reinterpret_cast<uptr>(old_mid_p);
 363   uptr new_mid = reinterpret_cast<uptr>(new_mid_p);
 364   uptr granularity = SHADOW_GRANULARITY;
 365   if (!(beg <= old_mid && beg <= new_mid && old_mid <= end && new_mid <= end &&
 366         IsAligned(beg, granularity))) {
 367     GET_STACK_TRACE_FATAL_HERE;
 368     ReportBadParamsToAnnotateContiguousContainer(beg, end, old_mid, new_mid,
 369                                                  &stack);
 370   }
 371   CHECK_LE(end - beg,
 372            FIRST_32_SECOND_64(1UL << 30, 1ULL << 34)); // Sanity check.
 373
 374   uptr a = RoundDownTo(Min(old_mid, new_mid), granularity);
 375   uptr c = RoundUpTo(Max(old_mid, new_mid), granularity);
 376   uptr d1 = RoundDownTo(old_mid, granularity);
 377   // uptr d2 = RoundUpTo(old_mid, granularity);
 378   // Currently we should be in this state:
 379   // [a, d1) is good, [d2, c) is bad, [d1, d2) is partially good.
 380   // Make a quick sanity check that we are indeed in this state.
 381   //
 382   // FIXME: Two of these three checks are disabled until we fix
 383   // https://github.com/google/sanitizers/issues/258.
 384   // if (d1 != d2)
 385   //  CHECK_EQ(*(u8*)MemToShadow(d1), old_mid - d1);
 386   if (a + granularity <= d1)
 387     CHECK_EQ(*(u8*)MemToShadow(a), 0);
 388   // if (d2 + granularity <= c && c <= end)
 389   //   CHECK_EQ(*(u8 *)MemToShadow(c - granularity),
 390   //            kAsanContiguousContainerOOBMagic);
 391
 392   uptr b1 = RoundDownTo(new_mid, granularity);
 393   uptr b2 = RoundUpTo(new_mid, granularity);
 394   // New state:
 395   // [a, b1) is good, [b2, c) is bad, [b1, b2) is partially good.
 396   PoisonShadow(a, b1 - a, 0);
 397   PoisonShadow(b2, c - b2, kAsanContiguousContainerOOBMagic);
 398   if (b1 != b2) {
 399     CHECK_EQ(b2 - b1, granularity);
 400     *(u8*)MemToShadow(b1) = static_cast<u8>(new_mid - b1);
 401   }
 402 }
 403
 404 const void *__sanitizer_contiguous_container_find_bad_address(
 405     const void *beg_p, const void *mid_p, const void *end_p) {
 406   if (!flags()->detect_container_overflow)
 407     return nullptr;
 408   uptr beg = reinterpret_cast<uptr>(beg_p);
 409   uptr end = reinterpret_cast<uptr>(end_p);
 410   uptr mid = reinterpret_cast<uptr>(mid_p);
 411   CHECK_LE(beg, mid);
 412   CHECK_LE(mid, end);
 413   // Check some bytes starting from beg, some bytes around mid, and some bytes
 414   // ending with end.
 415   uptr kMaxRangeToCheck = 32;
 416   uptr r1_beg = beg;
 417   uptr r1_end = Min(beg + kMaxRangeToCheck, mid);
 418   uptr r2_beg = Max(beg, mid - kMaxRangeToCheck);
 419   uptr r2_end = Min(end, mid + kMaxRangeToCheck);
 420   uptr r3_beg = Max(end - kMaxRangeToCheck, mid);
 421   uptr r3_end = end;
 422   for (uptr i = r1_beg; i < r1_end; i++)
 423     if (AddressIsPoisoned(i))
 424       return reinterpret_cast<const void *>(i);
 425   for (uptr i = r2_beg; i < mid; i++)
 426     if (AddressIsPoisoned(i))
 427       return reinterpret_cast<const void *>(i);
 428   for (uptr i = mid; i < r2_end; i++)
 429     if (!AddressIsPoisoned(i))
 430       return reinterpret_cast<const void *>(i);
 431   for (uptr i = r3_beg; i < r3_end; i++)
 432     if (!AddressIsPoisoned(i))
 433       return reinterpret_cast<const void *>(i);
 434   return nullptr;
 435 }
 436
 437 int __sanitizer_verify_contiguous_container(const void *beg_p,
 438                                             const void *mid_p,
 439                                             const void *end_p) {
 440   return __sanitizer_contiguous_container_find_bad_address(beg_p, mid_p,
 441                                                            end_p) == nullptr;
 442 }
 443
 444 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 445 void __asan_poison_intra_object_redzone(uptr ptr, uptr size) {
 446   AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, true);
 447 }
 448
 449 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 450 void __asan_unpoison_intra_object_redzone(uptr ptr, uptr size) {
 451   AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, false);
 452 }
 453
 454 // --- Implementation of LSan-specific functions --- {{{1
 455 namespace __lsan {
 456 bool WordIsPoisoned(uptr addr) {
 457   return (__asan_region_is_poisoned(addr, sizeof(uptr)) != 0);
 458 }
 459 }