| // Copyright (c) 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COMPONENTS_GWP_ASAN_CLIENT_GUARDED_PAGE_ALLOCATOR_H_ |
| #define COMPONENTS_GWP_ASAN_CLIENT_GUARDED_PAGE_ALLOCATOR_H_ |
| |
| #include <atomic> |
| #include <memory> |
| #include <string> |
| #include <vector> |
| |
| #include "base/callback.h" |
| #include "base/compiler_specific.h" |
| #include "base/gtest_prod_util.h" |
| #include "base/no_destructor.h" |
| #include "base/synchronization/lock.h" |
| #include "base/thread_annotations.h" |
| #include "components/gwp_asan/client/export.h" |
| #include "components/gwp_asan/common/allocator_state.h" |
| |
| namespace gwp_asan { |
| namespace internal { |
| |
| // This class encompasses the allocation and deallocation logic on top of the |
| // AllocatorState. Its members are not inspected or used by the crash handler. |
| // |
| // This class makes use of dynamically-sized arrays like std::vector<> to only |
| // allocate as much memory as we need; however, they only reserve memory at |
| // initialization-time so there is no risk of malloc reentrancy. |
| class GWP_ASAN_EXPORT GuardedPageAllocator { |
| public: |
| // Number of consecutive allocations that fail due to lack of available pages |
| // before we call the OOM callback. |
| static constexpr size_t kOutOfMemoryCount = 100; |
| // Default maximum alignment for all returned allocations. |
| static constexpr size_t kGpaAllocAlignment = 16; |
| |
| // Callback used to report the allocator running out of memory, reports the |
| // number of successful allocations before running out of memory. |
| using OutOfMemoryCallback = base::OnceCallback<void(size_t)>; |
| |
| // Does not allocate any memory for the allocator, to finish initializing call |
| // Init(). |
| GuardedPageAllocator(); |
| |
| // Configures this allocator to allocate up to max_alloced_pages pages at a |
| // time, holding metadata for up to num_metadata allocations, from a pool of |
| // total_pages pages, where: |
| // 1 <= max_alloced_pages <= num_metadata <= kMaxMetadata |
| // num_metadata <= total_pages <= kMaxSlots |
| // |
| // The OOM callback is called the first time the allocator fails to allocate |
| // kOutOfMemoryCount allocations consecutively due to lack of memory. |
| void Init(size_t max_alloced_pages, |
| size_t num_metadata, |
| size_t total_pages, |
| OutOfMemoryCallback oom_callback); |
| |
| // On success, returns a pointer to size bytes of page-guarded memory. On |
| // failure, returns nullptr. The allocation is not guaranteed to be |
| // zero-filled. Failure can occur if memory could not be mapped or protected, |
| // or if all guarded pages are already allocated. |
| // |
| // The align parameter specifies a power of two to align the allocation up to. |
| // It must be less than or equal to the allocation size. If it's left as zero |
| // it will default to the default alignment the allocator chooses. |
| // |
| // Preconditions: Init() must have been called. |
| void* Allocate(size_t size, size_t align = 0); |
| |
| // Deallocates memory pointed to by ptr. ptr must have been previously |
| // returned by a call to Allocate. |
| void Deallocate(void* ptr); |
| |
| // Returns the size requested when ptr was allocated. ptr must have been |
| // previously returned by a call to Allocate, and not have been deallocated. |
| size_t GetRequestedSize(const void* ptr) const; |
| |
| // Retrieves the textual address of the shared allocator state required by the |
| // crash handler. |
| std::string GetCrashKey() const; |
| |
| // Returns true if ptr points to memory managed by this class. |
| inline bool PointerIsMine(const void* ptr) const { |
| return state_.PointerIsMine(reinterpret_cast<uintptr_t>(ptr)); |
| } |
| |
| private: |
| // Manages a free list of slot or metadata indices in the range |
| // [0, max_entries). Access to SimpleFreeList objects must be synchronized. |
| // |
| // SimpleFreeList is specifically designed to pre-allocate data in Initialize |
| // so that it never recurses into malloc/free during Allocate/Free. |
| template <typename T> |
| class SimpleFreeList { |
| public: |
| void Initialize(T max_entries); |
| T Allocate(); |
| void Free(T entry); |
| |
| private: |
| std::vector<T> free_list_; |
| |
| // Number of used entries. This counter ensures all free entries are used |
| // before starting to use random eviction. |
| T num_used_entries_ = 0; |
| T max_entries_ = 0; |
| }; |
| |
| // Unmaps memory allocated by this class, if Init was called. |
| ~GuardedPageAllocator(); |
| |
| // Allocates/deallocates the virtual memory used for allocations. |
| void* MapRegion(); |
| void UnmapRegion(); |
| |
| // Returns the size of the virtual memory region used to store allocations. |
| size_t RegionSize() const; |
| |
| // Mark page read-write. |
| void MarkPageReadWrite(void*); |
| |
| // Mark page inaccessible and decommit the memory from use to save memory |
| // used by the quarantine. |
| void MarkPageInaccessible(void*); |
| |
| // On success, returns true and writes the reserved indices to |slot| and |
| // |metadata_idx|. Otherwise returns false if no allocations are available. |
| bool ReserveSlotAndMetadata(AllocatorState::SlotIdx* slot, |
| AllocatorState::MetadataIdx* metadata_idx) |
| LOCKS_EXCLUDED(lock_); |
| |
| // Marks the specified slot and metadata as unreserved. |
| void FreeSlotAndMetadata(AllocatorState::SlotIdx slot, |
| AllocatorState::MetadataIdx metadata_idx) |
| LOCKS_EXCLUDED(lock_); |
| |
| // Record the metadata for an allocation or deallocation for a given metadata |
| // index. |
| ALWAYS_INLINE |
| void RecordAllocationMetadata(AllocatorState::MetadataIdx metadata_idx, |
| size_t size, |
| void* ptr); |
| ALWAYS_INLINE void RecordDeallocationMetadata( |
| AllocatorState::MetadataIdx metadata_idx); |
| |
| // Allocator state shared with with the crash analyzer. |
| AllocatorState state_; |
| |
| // Lock that synchronizes allocating/freeing slots between threads. |
| base::Lock lock_; |
| |
| SimpleFreeList<AllocatorState::SlotIdx> free_slots_ GUARDED_BY(lock_); |
| SimpleFreeList<AllocatorState::MetadataIdx> free_metadata_ GUARDED_BY(lock_); |
| |
| // Number of currently-allocated pages. |
| size_t num_alloced_pages_ GUARDED_BY(lock_) = 0; |
| // Max number of concurrent allocations. |
| size_t max_alloced_pages_ = 0; |
| |
| // Array of metadata (e.g. stack traces) for allocations. |
| // TODO(vtsyrklevich): Use an std::vector<> here as well. |
| std::unique_ptr<AllocatorState::SlotMetadata[]> metadata_; |
| |
| // Maps a slot index to a metadata index (or kInvalidMetadataIdx if no such |
| // mapping exists.) |
| std::vector<AllocatorState::MetadataIdx> slot_to_metadata_idx_; |
| |
| // Maintain a count of total allocations and consecutive failed allocations |
| // to report allocator OOM. |
| size_t total_allocations_ GUARDED_BY(lock_) = 0; |
| size_t consecutive_failed_allocations_ GUARDED_BY(lock_) = 0; |
| bool oom_hit_ GUARDED_BY(lock_) = false; |
| OutOfMemoryCallback oom_callback_; |
| |
| // Required for a singleton to access the constructor. |
| friend base::NoDestructor<GuardedPageAllocator>; |
| |
| friend class CrashAnalyzerTest; |
| friend class GuardedPageAllocatorTest; |
| FRIEND_TEST_ALL_PREFIXES(CrashAnalyzerTest, InternalError); |
| FRIEND_TEST_ALL_PREFIXES(CrashAnalyzerTest, StackTraceCollection); |
| FRIEND_TEST_ALL_PREFIXES(GuardedPageAllocatorTest, |
| GetNearestValidPageEdgeCases); |
| FRIEND_TEST_ALL_PREFIXES(GuardedPageAllocatorTest, GetErrorTypeEdgeCases); |
| |
| DISALLOW_COPY_AND_ASSIGN(GuardedPageAllocator); |
| }; |
| |
| } // namespace internal |
| } // namespace gwp_asan |
| |
| #endif // COMPONENTS_GWP_ASAN_CLIENT_GUARDED_PAGE_ALLOCATOR_H_ |