1 //===-- asan_poisoning.cc -------------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
12 // Shadow memory poisoning by ASan RTL and by user application.
13 //===----------------------------------------------------------------------===//
15 #include "asan_poisoning.h"
16 #include "asan_report.h"
17 #include "asan_stack.h"
18 #include "sanitizer_common/sanitizer_atomic.h"
19 #include "sanitizer_common/sanitizer_libc.h"
20 #include "sanitizer_common/sanitizer_flags.h"
24 static atomic_uint8_t can_poison_memory;
26 void SetCanPoisonMemory(bool value) {
27 atomic_store(&can_poison_memory, value, memory_order_release);
30 bool CanPoisonMemory() {
31 return atomic_load(&can_poison_memory, memory_order_acquire);
34 void PoisonShadow(uptr addr, uptr size, u8 value) {
35 if (!CanPoisonMemory()) return;
36 CHECK(AddrIsAlignedByGranularity(addr));
37 CHECK(AddrIsInMem(addr));
38 CHECK(AddrIsAlignedByGranularity(addr + size));
39 CHECK(AddrIsInMem(addr + size - SHADOW_GRANULARITY));
41 FastPoisonShadow(addr, size, value);
44 void PoisonShadowPartialRightRedzone(uptr addr,
48 if (!CanPoisonMemory()) return;
49 CHECK(AddrIsAlignedByGranularity(addr));
50 CHECK(AddrIsInMem(addr));
51 FastPoisonShadowPartialRightRedzone(addr, size, redzone_size, value);
54 struct ShadowSegmentEndpoint {
56 s8 offset; // in [0, SHADOW_GRANULARITY)
57 s8 value; // = *chunk;
59 explicit ShadowSegmentEndpoint(uptr address) {
60 chunk = (u8*)MemToShadow(address);
61 offset = address & (SHADOW_GRANULARITY - 1);
66 void FlushUnneededASanShadowMemory(uptr p, uptr size) {
67 // Since asan's mapping is compacting, the shadow chunk may be
68 // not page-aligned, so we only flush the page-aligned portion.
69 uptr page_size = GetPageSizeCached();
70 uptr shadow_beg = RoundUpTo(MemToShadow(p), page_size);
71 uptr shadow_end = RoundDownTo(MemToShadow(p + size), page_size);
72 FlushUnneededShadowMemory(shadow_beg, shadow_end - shadow_beg);
75 void AsanPoisonOrUnpoisonIntraObjectRedzone(uptr ptr, uptr size, bool poison) {
76 uptr end = ptr + size;
78 Printf("__asan_%spoison_intra_object_redzone [%p,%p) %zd\n",
79 poison ? "" : "un", ptr, end, size);
81 PRINT_CURRENT_STACK();
85 CHECK(IsAligned(end, SHADOW_GRANULARITY));
86 if (!IsAligned(ptr, SHADOW_GRANULARITY)) {
87 *(u8 *)MemToShadow(ptr) =
88 poison ? static_cast<u8>(ptr % SHADOW_GRANULARITY) : 0;
89 ptr |= SHADOW_GRANULARITY - 1;
92 for (; ptr < end; ptr += SHADOW_GRANULARITY)
93 *(u8*)MemToShadow(ptr) = poison ? kAsanIntraObjectRedzone : 0;
98 // ---------------------- Interface ---------------- {{{1
99 using namespace __asan; // NOLINT
101 // Current implementation of __asan_(un)poison_memory_region doesn't check
102 // that user program (un)poisons the memory it owns. It poisons memory
103 // conservatively, and unpoisons progressively to make sure asan shadow
104 // mapping invariant is preserved (see detailed mapping description here:
105 // https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm).
107 // * if user asks to poison region [left, right), the program poisons
108 // at least [left, AlignDown(right)).
109 // * if user asks to unpoison region [left, right), the program unpoisons
110 // at most [AlignDown(left), right).
111 void __asan_poison_memory_region(void const volatile *addr, uptr size) {
112 if (!flags()->allow_user_poisoning || size == 0) return;
113 uptr beg_addr = (uptr)addr;
114 uptr end_addr = beg_addr + size;
115 VPrintf(3, "Trying to poison memory region [%p, %p)\n", (void *)beg_addr,
117 ShadowSegmentEndpoint beg(beg_addr);
118 ShadowSegmentEndpoint end(end_addr);
119 if (beg.chunk == end.chunk) {
120 CHECK(beg.offset < end.offset);
121 s8 value = beg.value;
122 CHECK(value == end.value);
123 // We can only poison memory if the byte in end.offset is unaddressable.
124 // No need to re-poison memory if it is poisoned already.
125 if (value > 0 && value <= end.offset) {
126 if (beg.offset > 0) {
127 *beg.chunk = Min(value, beg.offset);
129 *beg.chunk = kAsanUserPoisonedMemoryMagic;
134 CHECK(beg.chunk < end.chunk);
135 if (beg.offset > 0) {
136 // Mark bytes from beg.offset as unaddressable.
137 if (beg.value == 0) {
138 *beg.chunk = beg.offset;
140 *beg.chunk = Min(beg.value, beg.offset);
144 REAL(memset)(beg.chunk, kAsanUserPoisonedMemoryMagic, end.chunk - beg.chunk);
145 // Poison if byte in end.offset is unaddressable.
146 if (end.value > 0 && end.value <= end.offset) {
147 *end.chunk = kAsanUserPoisonedMemoryMagic;
151 void __asan_unpoison_memory_region(void const volatile *addr, uptr size) {
152 if (!flags()->allow_user_poisoning || size == 0) return;
153 uptr beg_addr = (uptr)addr;
154 uptr end_addr = beg_addr + size;
155 VPrintf(3, "Trying to unpoison memory region [%p, %p)\n", (void *)beg_addr,
157 ShadowSegmentEndpoint beg(beg_addr);
158 ShadowSegmentEndpoint end(end_addr);
159 if (beg.chunk == end.chunk) {
160 CHECK(beg.offset < end.offset);
161 s8 value = beg.value;
162 CHECK(value == end.value);
163 // We unpoison memory bytes up to enbytes up to end.offset if it is not
164 // unpoisoned already.
166 *beg.chunk = Max(value, end.offset);
170 CHECK(beg.chunk < end.chunk);
171 if (beg.offset > 0) {
175 REAL(memset)(beg.chunk, 0, end.chunk - beg.chunk);
176 if (end.offset > 0 && end.value != 0) {
177 *end.chunk = Max(end.value, end.offset);
181 int __asan_address_is_poisoned(void const volatile *addr) {
182 return __asan::AddressIsPoisoned((uptr)addr);
185 uptr __asan_region_is_poisoned(uptr beg, uptr size) {
187 uptr end = beg + size;
188 if (!AddrIsInMem(beg)) return beg;
189 if (!AddrIsInMem(end)) return end;
191 uptr aligned_b = RoundUpTo(beg, SHADOW_GRANULARITY);
192 uptr aligned_e = RoundDownTo(end, SHADOW_GRANULARITY);
193 uptr shadow_beg = MemToShadow(aligned_b);
194 uptr shadow_end = MemToShadow(aligned_e);
195 // First check the first and the last application bytes,
196 // then check the SHADOW_GRANULARITY-aligned region by calling
197 // mem_is_zero on the corresponding shadow.
198 if (!__asan::AddressIsPoisoned(beg) &&
199 !__asan::AddressIsPoisoned(end - 1) &&
200 (shadow_end <= shadow_beg ||
201 __sanitizer::mem_is_zero((const char *)shadow_beg,
202 shadow_end - shadow_beg)))
204 // The fast check failed, so we have a poisoned byte somewhere.
206 for (; beg < end; beg++)
207 if (__asan::AddressIsPoisoned(beg))
209 UNREACHABLE("mem_is_zero returned false, but poisoned byte was not found");
213 #define CHECK_SMALL_REGION(p, size, isWrite) \
215 uptr __p = reinterpret_cast<uptr>(p); \
216 uptr __size = size; \
217 if (UNLIKELY(__asan::AddressIsPoisoned(__p) || \
218 __asan::AddressIsPoisoned(__p + __size - 1))) { \
219 GET_CURRENT_PC_BP_SP; \
220 uptr __bad = __asan_region_is_poisoned(__p, __size); \
221 __asan_report_error(pc, bp, sp, __bad, isWrite, __size, 0);\
226 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
227 u16 __sanitizer_unaligned_load16(const uu16 *p) {
228 CHECK_SMALL_REGION(p, sizeof(*p), false);
232 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
233 u32 __sanitizer_unaligned_load32(const uu32 *p) {
234 CHECK_SMALL_REGION(p, sizeof(*p), false);
238 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
239 u64 __sanitizer_unaligned_load64(const uu64 *p) {
240 CHECK_SMALL_REGION(p, sizeof(*p), false);
244 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
245 void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
246 CHECK_SMALL_REGION(p, sizeof(*p), true);
250 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
251 void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
252 CHECK_SMALL_REGION(p, sizeof(*p), true);
256 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
257 void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
258 CHECK_SMALL_REGION(p, sizeof(*p), true);
262 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
263 void __asan_poison_cxx_array_cookie(uptr p) {
264 if (SANITIZER_WORDSIZE != 64) return;
265 if (!flags()->poison_array_cookie) return;
266 uptr s = MEM_TO_SHADOW(p);
267 *reinterpret_cast<u8*>(s) = kAsanArrayCookieMagic;
270 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
271 uptr __asan_load_cxx_array_cookie(uptr *p) {
272 if (SANITIZER_WORDSIZE != 64) return *p;
273 if (!flags()->poison_array_cookie) return *p;
274 uptr s = MEM_TO_SHADOW(reinterpret_cast<uptr>(p));
275 u8 sval = *reinterpret_cast<u8*>(s);
276 if (sval == kAsanArrayCookieMagic) return *p;
277 // If sval is not kAsanArrayCookieMagic it can only be freed memory,
278 // which means that we are going to get double-free. So, return 0 to avoid
279 // infinite loop of destructors. We don't want to report a double-free here
280 // though, so print a warning just in case.
281 // CHECK_EQ(sval, kAsanHeapFreeMagic);
282 if (sval == kAsanHeapFreeMagic) {
283 Report("AddressSanitizer: loaded array cookie from free-d memory; "
284 "expect a double-free report\n");
287 // The cookie may remain unpoisoned if e.g. it comes from a custom
288 // operator new defined inside a class.
292 // This is a simplified version of __asan_(un)poison_memory_region, which
293 // assumes that left border of region to be poisoned is properly aligned.
294 static void PoisonAlignedStackMemory(uptr addr, uptr size, bool do_poison) {
295 if (size == 0) return;
296 uptr aligned_size = size & ~(SHADOW_GRANULARITY - 1);
297 PoisonShadow(addr, aligned_size,
298 do_poison ? kAsanStackUseAfterScopeMagic : 0);
299 if (size == aligned_size)
301 s8 end_offset = (s8)(size - aligned_size);
302 s8* shadow_end = (s8*)MemToShadow(addr + aligned_size);
303 s8 end_value = *shadow_end;
305 // If possible, mark all the bytes mapping to last shadow byte as
307 if (end_value > 0 && end_value <= end_offset)
308 *shadow_end = (s8)kAsanStackUseAfterScopeMagic;
310 // If necessary, mark few first bytes mapping to last shadow byte
313 *shadow_end = Max(end_value, end_offset);
317 void __asan_poison_stack_memory(uptr addr, uptr size) {
318 VReport(1, "poisoning: %p %zx\n", (void *)addr, size);
319 PoisonAlignedStackMemory(addr, size, true);
322 void __asan_unpoison_stack_memory(uptr addr, uptr size) {
323 VReport(1, "unpoisoning: %p %zx\n", (void *)addr, size);
324 PoisonAlignedStackMemory(addr, size, false);
327 void __sanitizer_annotate_contiguous_container(const void *beg_p,
329 const void *old_mid_p,
330 const void *new_mid_p) {
331 if (!flags()->detect_container_overflow) return;
332 VPrintf(2, "contiguous_container: %p %p %p %p\n", beg_p, end_p, old_mid_p,
334 uptr beg = reinterpret_cast<uptr>(beg_p);
335 uptr end = reinterpret_cast<uptr>(end_p);
336 uptr old_mid = reinterpret_cast<uptr>(old_mid_p);
337 uptr new_mid = reinterpret_cast<uptr>(new_mid_p);
338 uptr granularity = SHADOW_GRANULARITY;
339 if (!(beg <= old_mid && beg <= new_mid && old_mid <= end && new_mid <= end &&
340 IsAligned(beg, granularity))) {
341 GET_STACK_TRACE_FATAL_HERE;
342 ReportBadParamsToAnnotateContiguousContainer(beg, end, old_mid, new_mid,
346 FIRST_32_SECOND_64(1UL << 30, 1UL << 34)); // Sanity check.
348 uptr a = RoundDownTo(Min(old_mid, new_mid), granularity);
349 uptr c = RoundUpTo(Max(old_mid, new_mid), granularity);
350 uptr d1 = RoundDownTo(old_mid, granularity);
351 // uptr d2 = RoundUpTo(old_mid, granularity);
352 // Currently we should be in this state:
353 // [a, d1) is good, [d2, c) is bad, [d1, d2) is partially good.
354 // Make a quick sanity check that we are indeed in this state.
356 // FIXME: Two of these three checks are disabled until we fix
357 // https://github.com/google/sanitizers/issues/258.
359 // CHECK_EQ(*(u8*)MemToShadow(d1), old_mid - d1);
360 if (a + granularity <= d1)
361 CHECK_EQ(*(u8*)MemToShadow(a), 0);
362 // if (d2 + granularity <= c && c <= end)
363 // CHECK_EQ(*(u8 *)MemToShadow(c - granularity),
364 // kAsanContiguousContainerOOBMagic);
366 uptr b1 = RoundDownTo(new_mid, granularity);
367 uptr b2 = RoundUpTo(new_mid, granularity);
369 // [a, b1) is good, [b2, c) is bad, [b1, b2) is partially good.
370 PoisonShadow(a, b1 - a, 0);
371 PoisonShadow(b2, c - b2, kAsanContiguousContainerOOBMagic);
373 CHECK_EQ(b2 - b1, granularity);
374 *(u8*)MemToShadow(b1) = static_cast<u8>(new_mid - b1);
378 const void *__sanitizer_contiguous_container_find_bad_address(
379 const void *beg_p, const void *mid_p, const void *end_p) {
380 if (!flags()->detect_container_overflow)
382 uptr beg = reinterpret_cast<uptr>(beg_p);
383 uptr end = reinterpret_cast<uptr>(end_p);
384 uptr mid = reinterpret_cast<uptr>(mid_p);
387 // Check some bytes starting from beg, some bytes around mid, and some bytes
389 uptr kMaxRangeToCheck = 32;
391 uptr r1_end = Min(end + kMaxRangeToCheck, mid);
392 uptr r2_beg = Max(beg, mid - kMaxRangeToCheck);
393 uptr r2_end = Min(end, mid + kMaxRangeToCheck);
394 uptr r3_beg = Max(end - kMaxRangeToCheck, mid);
396 for (uptr i = r1_beg; i < r1_end; i++)
397 if (AddressIsPoisoned(i))
398 return reinterpret_cast<const void *>(i);
399 for (uptr i = r2_beg; i < mid; i++)
400 if (AddressIsPoisoned(i))
401 return reinterpret_cast<const void *>(i);
402 for (uptr i = mid; i < r2_end; i++)
403 if (!AddressIsPoisoned(i))
404 return reinterpret_cast<const void *>(i);
405 for (uptr i = r3_beg; i < r3_end; i++)
406 if (!AddressIsPoisoned(i))
407 return reinterpret_cast<const void *>(i);
411 int __sanitizer_verify_contiguous_container(const void *beg_p,
414 return __sanitizer_contiguous_container_find_bad_address(beg_p, mid_p,
418 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
419 void __asan_poison_intra_object_redzone(uptr ptr, uptr size) {
420 AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, true);
423 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
424 void __asan_unpoison_intra_object_redzone(uptr ptr, uptr size) {
425 AsanPoisonOrUnpoisonIntraObjectRedzone(ptr, size, false);
428 // --- Implementation of LSan-specific functions --- {{{1
430 bool WordIsPoisoned(uptr addr) {
431 return (__asan_region_is_poisoned(addr, sizeof(uptr)) != 0);