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1 //===-- hwasan_allocator.cpp ------------------------ ---------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of HWAddressSanitizer.
10 //
11 // HWAddressSanitizer allocator.
12 //===----------------------------------------------------------------------===//
13 
14 #include "sanitizer_common/sanitizer_atomic.h"
15 #include "sanitizer_common/sanitizer_errno.h"
16 #include "sanitizer_common/sanitizer_stackdepot.h"
17 #include "hwasan.h"
18 #include "hwasan_allocator.h"
19 #include "hwasan_checks.h"
20 #include "hwasan_mapping.h"
21 #include "hwasan_malloc_bisect.h"
22 #include "hwasan_thread.h"
23 #include "hwasan_report.h"
24 
25 namespace __hwasan {
26 
27 static Allocator allocator;
28 static AllocatorCache fallback_allocator_cache;
29 static SpinMutex fallback_mutex;
30 static atomic_uint8_t hwasan_allocator_tagging_enabled;
31 
32 static const tag_t kFallbackAllocTag = 0xBB;
33 static const tag_t kFallbackFreeTag = 0xBC;
34 
35 enum RightAlignMode {
36   kRightAlignNever,
37   kRightAlignSometimes,
38   kRightAlignAlways
39 };
40 
41 // Initialized in HwasanAllocatorInit, an never changed.
42 static ALIGNED(16) u8 tail_magic[kShadowAlignment - 1];
43 
IsAllocated() const44 bool HwasanChunkView::IsAllocated() const {
45   return metadata_ && metadata_->alloc_context_id &&
46          metadata_->get_requested_size();
47 }
48 
49 // Aligns the 'addr' right to the granule boundary.
AlignRight(uptr addr,uptr requested_size)50 static uptr AlignRight(uptr addr, uptr requested_size) {
51   uptr tail_size = requested_size % kShadowAlignment;
52   if (!tail_size) return addr;
53   return addr + kShadowAlignment - tail_size;
54 }
55 
Beg() const56 uptr HwasanChunkView::Beg() const {
57   if (metadata_ && metadata_->right_aligned)
58     return AlignRight(block_, metadata_->get_requested_size());
59   return block_;
60 }
End() const61 uptr HwasanChunkView::End() const {
62   return Beg() + UsedSize();
63 }
UsedSize() const64 uptr HwasanChunkView::UsedSize() const {
65   return metadata_->get_requested_size();
66 }
GetAllocStackId() const67 u32 HwasanChunkView::GetAllocStackId() const {
68   return metadata_->alloc_context_id;
69 }
70 
ActualSize() const71 uptr HwasanChunkView::ActualSize() const {
72   return allocator.GetActuallyAllocatedSize(reinterpret_cast<void *>(block_));
73 }
74 
FromSmallHeap() const75 bool HwasanChunkView::FromSmallHeap() const {
76   return allocator.FromPrimary(reinterpret_cast<void *>(block_));
77 }
78 
GetAllocatorStats(AllocatorStatCounters s)79 void GetAllocatorStats(AllocatorStatCounters s) {
80   allocator.GetStats(s);
81 }
82 
HwasanAllocatorInit()83 void HwasanAllocatorInit() {
84   atomic_store_relaxed(&hwasan_allocator_tagging_enabled,
85                        !flags()->disable_allocator_tagging);
86   SetAllocatorMayReturnNull(common_flags()->allocator_may_return_null);
87   allocator.Init(common_flags()->allocator_release_to_os_interval_ms);
88   for (uptr i = 0; i < sizeof(tail_magic); i++)
89     tail_magic[i] = GetCurrentThread()->GenerateRandomTag();
90 }
91 
AllocatorSwallowThreadLocalCache(AllocatorCache * cache)92 void AllocatorSwallowThreadLocalCache(AllocatorCache *cache) {
93   allocator.SwallowCache(cache);
94 }
95 
TaggedSize(uptr size)96 static uptr TaggedSize(uptr size) {
97   if (!size) size = 1;
98   uptr new_size = RoundUpTo(size, kShadowAlignment);
99   CHECK_GE(new_size, size);
100   return new_size;
101 }
102 
HwasanAllocate(StackTrace * stack,uptr orig_size,uptr alignment,bool zeroise)103 static void *HwasanAllocate(StackTrace *stack, uptr orig_size, uptr alignment,
104                             bool zeroise) {
105   if (orig_size > kMaxAllowedMallocSize) {
106     if (AllocatorMayReturnNull()) {
107       Report("WARNING: HWAddressSanitizer failed to allocate 0x%zx bytes\n",
108              orig_size);
109       return nullptr;
110     }
111     ReportAllocationSizeTooBig(orig_size, kMaxAllowedMallocSize, stack);
112   }
113 
114   alignment = Max(alignment, kShadowAlignment);
115   uptr size = TaggedSize(orig_size);
116   Thread *t = GetCurrentThread();
117   void *allocated;
118   if (t) {
119     allocated = allocator.Allocate(t->allocator_cache(), size, alignment);
120   } else {
121     SpinMutexLock l(&fallback_mutex);
122     AllocatorCache *cache = &fallback_allocator_cache;
123     allocated = allocator.Allocate(cache, size, alignment);
124   }
125   if (UNLIKELY(!allocated)) {
126     SetAllocatorOutOfMemory();
127     if (AllocatorMayReturnNull())
128       return nullptr;
129     ReportOutOfMemory(size, stack);
130   }
131   Metadata *meta =
132       reinterpret_cast<Metadata *>(allocator.GetMetaData(allocated));
133   meta->set_requested_size(orig_size);
134   meta->alloc_context_id = StackDepotPut(*stack);
135   meta->right_aligned = false;
136   if (zeroise) {
137     internal_memset(allocated, 0, size);
138   } else if (flags()->max_malloc_fill_size > 0) {
139     uptr fill_size = Min(size, (uptr)flags()->max_malloc_fill_size);
140     internal_memset(allocated, flags()->malloc_fill_byte, fill_size);
141   }
142   if (size != orig_size) {
143     internal_memcpy(reinterpret_cast<u8 *>(allocated) + orig_size, tail_magic,
144                     size - orig_size - 1);
145   }
146 
147   void *user_ptr = allocated;
148   // Tagging can only be skipped when both tag_in_malloc and tag_in_free are
149   // false. When tag_in_malloc = false and tag_in_free = true malloc needs to
150   // retag to 0.
151   if ((flags()->tag_in_malloc || flags()->tag_in_free) &&
152       atomic_load_relaxed(&hwasan_allocator_tagging_enabled)) {
153     if (flags()->tag_in_malloc && malloc_bisect(stack, orig_size)) {
154       tag_t tag = t ? t->GenerateRandomTag() : kFallbackAllocTag;
155       uptr tag_size = orig_size ? orig_size : 1;
156       uptr full_granule_size = RoundDownTo(tag_size, kShadowAlignment);
157       user_ptr =
158           (void *)TagMemoryAligned((uptr)user_ptr, full_granule_size, tag);
159       if (full_granule_size != tag_size) {
160         u8 *short_granule =
161             reinterpret_cast<u8 *>(allocated) + full_granule_size;
162         TagMemoryAligned((uptr)short_granule, kShadowAlignment,
163                          tag_size % kShadowAlignment);
164         short_granule[kShadowAlignment - 1] = tag;
165       }
166     } else {
167       user_ptr = (void *)TagMemoryAligned((uptr)user_ptr, size, 0);
168     }
169   }
170 
171   HWASAN_MALLOC_HOOK(user_ptr, size);
172   return user_ptr;
173 }
174 
PointerAndMemoryTagsMatch(void * tagged_ptr)175 static bool PointerAndMemoryTagsMatch(void *tagged_ptr) {
176   CHECK(tagged_ptr);
177   uptr tagged_uptr = reinterpret_cast<uptr>(tagged_ptr);
178   tag_t mem_tag = *reinterpret_cast<tag_t *>(
179       MemToShadow(reinterpret_cast<uptr>(UntagPtr(tagged_ptr))));
180   return PossiblyShortTagMatches(mem_tag, tagged_uptr, 1);
181 }
182 
HwasanDeallocate(StackTrace * stack,void * tagged_ptr)183 static void HwasanDeallocate(StackTrace *stack, void *tagged_ptr) {
184   CHECK(tagged_ptr);
185   HWASAN_FREE_HOOK(tagged_ptr);
186 
187   if (!PointerAndMemoryTagsMatch(tagged_ptr))
188     ReportInvalidFree(stack, reinterpret_cast<uptr>(tagged_ptr));
189 
190   void *untagged_ptr = UntagPtr(tagged_ptr);
191   void *aligned_ptr = reinterpret_cast<void *>(
192       RoundDownTo(reinterpret_cast<uptr>(untagged_ptr), kShadowAlignment));
193   Metadata *meta =
194       reinterpret_cast<Metadata *>(allocator.GetMetaData(aligned_ptr));
195   uptr orig_size = meta->get_requested_size();
196   u32 free_context_id = StackDepotPut(*stack);
197   u32 alloc_context_id = meta->alloc_context_id;
198 
199   // Check tail magic.
200   uptr tagged_size = TaggedSize(orig_size);
201   if (flags()->free_checks_tail_magic && orig_size &&
202       tagged_size != orig_size) {
203     uptr tail_size = tagged_size - orig_size - 1;
204     CHECK_LT(tail_size, kShadowAlignment);
205     void *tail_beg = reinterpret_cast<void *>(
206         reinterpret_cast<uptr>(aligned_ptr) + orig_size);
207     if (tail_size && internal_memcmp(tail_beg, tail_magic, tail_size))
208       ReportTailOverwritten(stack, reinterpret_cast<uptr>(tagged_ptr),
209                             orig_size, tail_magic);
210   }
211 
212   meta->set_requested_size(0);
213   meta->alloc_context_id = 0;
214   // This memory will not be reused by anyone else, so we are free to keep it
215   // poisoned.
216   Thread *t = GetCurrentThread();
217   if (flags()->max_free_fill_size > 0) {
218     uptr fill_size =
219         Min(TaggedSize(orig_size), (uptr)flags()->max_free_fill_size);
220     internal_memset(aligned_ptr, flags()->free_fill_byte, fill_size);
221   }
222   if (flags()->tag_in_free && malloc_bisect(stack, 0) &&
223       atomic_load_relaxed(&hwasan_allocator_tagging_enabled))
224     TagMemoryAligned(reinterpret_cast<uptr>(aligned_ptr), TaggedSize(orig_size),
225                      t ? t->GenerateRandomTag() : kFallbackFreeTag);
226   if (t) {
227     allocator.Deallocate(t->allocator_cache(), aligned_ptr);
228     if (auto *ha = t->heap_allocations())
229       ha->push({reinterpret_cast<uptr>(tagged_ptr), alloc_context_id,
230                 free_context_id, static_cast<u32>(orig_size)});
231   } else {
232     SpinMutexLock l(&fallback_mutex);
233     AllocatorCache *cache = &fallback_allocator_cache;
234     allocator.Deallocate(cache, aligned_ptr);
235   }
236 }
237 
HwasanReallocate(StackTrace * stack,void * tagged_ptr_old,uptr new_size,uptr alignment)238 static void *HwasanReallocate(StackTrace *stack, void *tagged_ptr_old,
239                               uptr new_size, uptr alignment) {
240   if (!PointerAndMemoryTagsMatch(tagged_ptr_old))
241     ReportInvalidFree(stack, reinterpret_cast<uptr>(tagged_ptr_old));
242 
243   void *tagged_ptr_new =
244       HwasanAllocate(stack, new_size, alignment, false /*zeroise*/);
245   if (tagged_ptr_old && tagged_ptr_new) {
246     void *untagged_ptr_old =  UntagPtr(tagged_ptr_old);
247     Metadata *meta =
248         reinterpret_cast<Metadata *>(allocator.GetMetaData(untagged_ptr_old));
249     internal_memcpy(
250         UntagPtr(tagged_ptr_new), untagged_ptr_old,
251         Min(new_size, static_cast<uptr>(meta->get_requested_size())));
252     HwasanDeallocate(stack, tagged_ptr_old);
253   }
254   return tagged_ptr_new;
255 }
256 
HwasanCalloc(StackTrace * stack,uptr nmemb,uptr size)257 static void *HwasanCalloc(StackTrace *stack, uptr nmemb, uptr size) {
258   if (UNLIKELY(CheckForCallocOverflow(size, nmemb))) {
259     if (AllocatorMayReturnNull())
260       return nullptr;
261     ReportCallocOverflow(nmemb, size, stack);
262   }
263   return HwasanAllocate(stack, nmemb * size, sizeof(u64), true);
264 }
265 
FindHeapChunkByAddress(uptr address)266 HwasanChunkView FindHeapChunkByAddress(uptr address) {
267   void *block = allocator.GetBlockBegin(reinterpret_cast<void*>(address));
268   if (!block)
269     return HwasanChunkView();
270   Metadata *metadata =
271       reinterpret_cast<Metadata*>(allocator.GetMetaData(block));
272   return HwasanChunkView(reinterpret_cast<uptr>(block), metadata);
273 }
274 
AllocationSize(const void * tagged_ptr)275 static uptr AllocationSize(const void *tagged_ptr) {
276   const void *untagged_ptr = UntagPtr(tagged_ptr);
277   if (!untagged_ptr) return 0;
278   const void *beg = allocator.GetBlockBegin(untagged_ptr);
279   Metadata *b = (Metadata *)allocator.GetMetaData(untagged_ptr);
280   if (b->right_aligned) {
281     if (beg != reinterpret_cast<void *>(RoundDownTo(
282                    reinterpret_cast<uptr>(untagged_ptr), kShadowAlignment)))
283       return 0;
284   } else {
285     if (beg != untagged_ptr) return 0;
286   }
287   return b->get_requested_size();
288 }
289 
hwasan_malloc(uptr size,StackTrace * stack)290 void *hwasan_malloc(uptr size, StackTrace *stack) {
291   return SetErrnoOnNull(HwasanAllocate(stack, size, sizeof(u64), false));
292 }
293 
hwasan_calloc(uptr nmemb,uptr size,StackTrace * stack)294 void *hwasan_calloc(uptr nmemb, uptr size, StackTrace *stack) {
295   return SetErrnoOnNull(HwasanCalloc(stack, nmemb, size));
296 }
297 
hwasan_realloc(void * ptr,uptr size,StackTrace * stack)298 void *hwasan_realloc(void *ptr, uptr size, StackTrace *stack) {
299   if (!ptr)
300     return SetErrnoOnNull(HwasanAllocate(stack, size, sizeof(u64), false));
301   if (size == 0) {
302     HwasanDeallocate(stack, ptr);
303     return nullptr;
304   }
305   return SetErrnoOnNull(HwasanReallocate(stack, ptr, size, sizeof(u64)));
306 }
307 
hwasan_reallocarray(void * ptr,uptr nmemb,uptr size,StackTrace * stack)308 void *hwasan_reallocarray(void *ptr, uptr nmemb, uptr size, StackTrace *stack) {
309   if (UNLIKELY(CheckForCallocOverflow(size, nmemb))) {
310     errno = errno_ENOMEM;
311     if (AllocatorMayReturnNull())
312       return nullptr;
313     ReportReallocArrayOverflow(nmemb, size, stack);
314   }
315   return hwasan_realloc(ptr, nmemb * size, stack);
316 }
317 
hwasan_valloc(uptr size,StackTrace * stack)318 void *hwasan_valloc(uptr size, StackTrace *stack) {
319   return SetErrnoOnNull(
320       HwasanAllocate(stack, size, GetPageSizeCached(), false));
321 }
322 
hwasan_pvalloc(uptr size,StackTrace * stack)323 void *hwasan_pvalloc(uptr size, StackTrace *stack) {
324   uptr PageSize = GetPageSizeCached();
325   if (UNLIKELY(CheckForPvallocOverflow(size, PageSize))) {
326     errno = errno_ENOMEM;
327     if (AllocatorMayReturnNull())
328       return nullptr;
329     ReportPvallocOverflow(size, stack);
330   }
331   // pvalloc(0) should allocate one page.
332   size = size ? RoundUpTo(size, PageSize) : PageSize;
333   return SetErrnoOnNull(HwasanAllocate(stack, size, PageSize, false));
334 }
335 
hwasan_aligned_alloc(uptr alignment,uptr size,StackTrace * stack)336 void *hwasan_aligned_alloc(uptr alignment, uptr size, StackTrace *stack) {
337   if (UNLIKELY(!CheckAlignedAllocAlignmentAndSize(alignment, size))) {
338     errno = errno_EINVAL;
339     if (AllocatorMayReturnNull())
340       return nullptr;
341     ReportInvalidAlignedAllocAlignment(size, alignment, stack);
342   }
343   return SetErrnoOnNull(HwasanAllocate(stack, size, alignment, false));
344 }
345 
hwasan_memalign(uptr alignment,uptr size,StackTrace * stack)346 void *hwasan_memalign(uptr alignment, uptr size, StackTrace *stack) {
347   if (UNLIKELY(!IsPowerOfTwo(alignment))) {
348     errno = errno_EINVAL;
349     if (AllocatorMayReturnNull())
350       return nullptr;
351     ReportInvalidAllocationAlignment(alignment, stack);
352   }
353   return SetErrnoOnNull(HwasanAllocate(stack, size, alignment, false));
354 }
355 
hwasan_posix_memalign(void ** memptr,uptr alignment,uptr size,StackTrace * stack)356 int hwasan_posix_memalign(void **memptr, uptr alignment, uptr size,
357                         StackTrace *stack) {
358   if (UNLIKELY(!CheckPosixMemalignAlignment(alignment))) {
359     if (AllocatorMayReturnNull())
360       return errno_EINVAL;
361     ReportInvalidPosixMemalignAlignment(alignment, stack);
362   }
363   void *ptr = HwasanAllocate(stack, size, alignment, false);
364   if (UNLIKELY(!ptr))
365     // OOM error is already taken care of by HwasanAllocate.
366     return errno_ENOMEM;
367   CHECK(IsAligned((uptr)ptr, alignment));
368   *(void **)UntagPtr(memptr) = ptr;
369   return 0;
370 }
371 
hwasan_free(void * ptr,StackTrace * stack)372 void hwasan_free(void *ptr, StackTrace *stack) {
373   return HwasanDeallocate(stack, ptr);
374 }
375 
376 }  // namespace __hwasan
377 
378 using namespace __hwasan;
379 
__hwasan_enable_allocator_tagging()380 void __hwasan_enable_allocator_tagging() {
381   atomic_store_relaxed(&hwasan_allocator_tagging_enabled, 1);
382 }
383 
__hwasan_disable_allocator_tagging()384 void __hwasan_disable_allocator_tagging() {
385   atomic_store_relaxed(&hwasan_allocator_tagging_enabled, 0);
386 }
387 
__sanitizer_get_current_allocated_bytes()388 uptr __sanitizer_get_current_allocated_bytes() {
389   uptr stats[AllocatorStatCount];
390   allocator.GetStats(stats);
391   return stats[AllocatorStatAllocated];
392 }
393 
__sanitizer_get_heap_size()394 uptr __sanitizer_get_heap_size() {
395   uptr stats[AllocatorStatCount];
396   allocator.GetStats(stats);
397   return stats[AllocatorStatMapped];
398 }
399 
__sanitizer_get_free_bytes()400 uptr __sanitizer_get_free_bytes() { return 1; }
401 
__sanitizer_get_unmapped_bytes()402 uptr __sanitizer_get_unmapped_bytes() { return 1; }
403 
__sanitizer_get_estimated_allocated_size(uptr size)404 uptr __sanitizer_get_estimated_allocated_size(uptr size) { return size; }
405 
__sanitizer_get_ownership(const void * p)406 int __sanitizer_get_ownership(const void *p) { return AllocationSize(p) != 0; }
407 
__sanitizer_get_allocated_size(const void * p)408 uptr __sanitizer_get_allocated_size(const void *p) { return AllocationSize(p); }
409