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