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llvm-project/compiler-rt/lib/scudo/scudo_allocator.cpp

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//===-- scudo_allocator.cpp -------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// Scudo Hardened Allocator implementation.
/// It uses the sanitizer_common allocator as a base and aims at mitigating
/// heap corruption vulnerabilities. It provides a checksum-guarded chunk
/// header, a delayed free list, and additional sanity checks.
///
//===----------------------------------------------------------------------===//
#include "scudo_allocator.h"
#include "scudo_crc32.h"
#include "scudo_errors.h"
#include "scudo_flags.h"
#include "scudo_interface_internal.h"
#include "scudo_tsd.h"
#include "scudo_utils.h"
#include "sanitizer_common/sanitizer_allocator_checks.h"
#include "sanitizer_common/sanitizer_allocator_interface.h"
#include "sanitizer_common/sanitizer_quarantine.h"
#ifdef GWP_ASAN_HOOKS
# include "gwp_asan/guarded_pool_allocator.h"
# include "gwp_asan/optional/backtrace.h"
# include "gwp_asan/optional/options_parser.h"
#endif // GWP_ASAN_HOOKS
#include <errno.h>
#include <string.h>
namespace __scudo {
// Global static cookie, initialized at start-up.
static u32 Cookie;
// We default to software CRC32 if the alternatives are not supported, either
// at compilation or at runtime.
static atomic_uint8_t HashAlgorithm = { CRC32Software };
INLINE u32 computeCRC32(u32 Crc, uptr Value, uptr *Array, uptr ArraySize) {
// If the hardware CRC32 feature is defined here, it was enabled everywhere,
// as opposed to only for scudo_crc32.cpp. This means that other hardware
// specific instructions were likely emitted at other places, and as a
// result there is no reason to not use it here.
#if defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
Crc = CRC32_INTRINSIC(Crc, Value);
for (uptr i = 0; i < ArraySize; i++)
Crc = CRC32_INTRINSIC(Crc, Array[i]);
return Crc;
#else
if (atomic_load_relaxed(&HashAlgorithm) == CRC32Hardware) {
Crc = computeHardwareCRC32(Crc, Value);
for (uptr i = 0; i < ArraySize; i++)
Crc = computeHardwareCRC32(Crc, Array[i]);
return Crc;
}
Crc = computeSoftwareCRC32(Crc, Value);
for (uptr i = 0; i < ArraySize; i++)
Crc = computeSoftwareCRC32(Crc, Array[i]);
return Crc;
#endif // defined(__SSE4_2__) || defined(__ARM_FEATURE_CRC32)
}
static BackendT &getBackend();
namespace Chunk {
static INLINE AtomicPackedHeader *getAtomicHeader(void *Ptr) {
return reinterpret_cast<AtomicPackedHeader *>(reinterpret_cast<uptr>(Ptr) -
getHeaderSize());
}
static INLINE
const AtomicPackedHeader *getConstAtomicHeader(const void *Ptr) {
return reinterpret_cast<const AtomicPackedHeader *>(
reinterpret_cast<uptr>(Ptr) - getHeaderSize());
}
static INLINE bool isAligned(const void *Ptr) {
return IsAligned(reinterpret_cast<uptr>(Ptr), MinAlignment);
}
// We can't use the offset member of the chunk itself, as we would double
// fetch it without any warranty that it wouldn't have been tampered. To
// prevent this, we work with a local copy of the header.
static INLINE void *getBackendPtr(const void *Ptr, UnpackedHeader *Header) {
return reinterpret_cast<void *>(reinterpret_cast<uptr>(Ptr) -
getHeaderSize() - (Header->Offset << MinAlignmentLog));
}
// Returns the usable size for a chunk, meaning the amount of bytes from the
// beginning of the user data to the end of the backend allocated chunk.
static INLINE uptr getUsableSize(const void *Ptr, UnpackedHeader *Header) {
const uptr ClassId = Header->ClassId;
if (ClassId)
return PrimaryT::ClassIdToSize(ClassId) - getHeaderSize() -
(Header->Offset << MinAlignmentLog);
return SecondaryT::GetActuallyAllocatedSize(
getBackendPtr(Ptr, Header)) - getHeaderSize();
}
// Returns the size the user requested when allocating the chunk.
static INLINE uptr getSize(const void *Ptr, UnpackedHeader *Header) {
const uptr SizeOrUnusedBytes = Header->SizeOrUnusedBytes;
if (Header->ClassId)
return SizeOrUnusedBytes;
return SecondaryT::GetActuallyAllocatedSize(
getBackendPtr(Ptr, Header)) - getHeaderSize() - SizeOrUnusedBytes;
}
// Compute the checksum of the chunk pointer and its header.
static INLINE u16 computeChecksum(const void *Ptr, UnpackedHeader *Header) {
UnpackedHeader ZeroChecksumHeader = *Header;
ZeroChecksumHeader.Checksum = 0;
uptr HeaderHolder[sizeof(UnpackedHeader) / sizeof(uptr)];
memcpy(&HeaderHolder, &ZeroChecksumHeader, sizeof(HeaderHolder));
const u32 Crc = computeCRC32(Cookie, reinterpret_cast<uptr>(Ptr),
HeaderHolder, ARRAY_SIZE(HeaderHolder));
return static_cast<u16>(Crc);
}
// Checks the validity of a chunk by verifying its checksum. It doesn't
// incur termination in the event of an invalid chunk.
static INLINE bool isValid(const void *Ptr) {
PackedHeader NewPackedHeader =
atomic_load_relaxed(getConstAtomicHeader(Ptr));
UnpackedHeader NewUnpackedHeader =
bit_cast<UnpackedHeader>(NewPackedHeader);
return (NewUnpackedHeader.Checksum ==
computeChecksum(Ptr, &NewUnpackedHeader));
}
// Ensure that ChunkAvailable is 0, so that if a 0 checksum is ever valid
// for a fully nulled out header, its state will be available anyway.
COMPILER_CHECK(ChunkAvailable == 0);
// Loads and unpacks the header, verifying the checksum in the process.
static INLINE
void loadHeader(const void *Ptr, UnpackedHeader *NewUnpackedHeader) {
PackedHeader NewPackedHeader =
atomic_load_relaxed(getConstAtomicHeader(Ptr));
*NewUnpackedHeader = bit_cast<UnpackedHeader>(NewPackedHeader);
if (UNLIKELY(NewUnpackedHeader->Checksum !=
computeChecksum(Ptr, NewUnpackedHeader)))
dieWithMessage("corrupted chunk header at address %p\n", Ptr);
}
// Packs and stores the header, computing the checksum in the process.
static INLINE void storeHeader(void *Ptr, UnpackedHeader *NewUnpackedHeader) {
NewUnpackedHeader->Checksum = computeChecksum(Ptr, NewUnpackedHeader);
PackedHeader NewPackedHeader = bit_cast<PackedHeader>(*NewUnpackedHeader);
atomic_store_relaxed(getAtomicHeader(Ptr), NewPackedHeader);
}
// Packs and stores the header, computing the checksum in the process. We
// compare the current header with the expected provided one to ensure that
// we are not being raced by a corruption occurring in another thread.
static INLINE void compareExchangeHeader(void *Ptr,
UnpackedHeader *NewUnpackedHeader,
UnpackedHeader *OldUnpackedHeader) {
NewUnpackedHeader->Checksum = computeChecksum(Ptr, NewUnpackedHeader);
PackedHeader NewPackedHeader = bit_cast<PackedHeader>(*NewUnpackedHeader);
PackedHeader OldPackedHeader = bit_cast<PackedHeader>(*OldUnpackedHeader);
if (UNLIKELY(!atomic_compare_exchange_strong(
getAtomicHeader(Ptr), &OldPackedHeader, NewPackedHeader,
memory_order_relaxed)))
dieWithMessage("race on chunk header at address %p\n", Ptr);
}
} // namespace Chunk
struct QuarantineCallback {
explicit QuarantineCallback(AllocatorCacheT *Cache)
: Cache_(Cache) {}
// Chunk recycling function, returns a quarantined chunk to the backend,
// first making sure it hasn't been tampered with.
void Recycle(void *Ptr) {
UnpackedHeader Header;
Chunk::loadHeader(Ptr, &Header);
if (UNLIKELY(Header.State != ChunkQuarantine))
dieWithMessage("invalid chunk state when recycling address %p\n", Ptr);
UnpackedHeader NewHeader = Header;
NewHeader.State = ChunkAvailable;
Chunk::compareExchangeHeader(Ptr, &NewHeader, &Header);
void *BackendPtr = Chunk::getBackendPtr(Ptr, &Header);
if (Header.ClassId)
getBackend().deallocatePrimary(Cache_, BackendPtr, Header.ClassId);
else
getBackend().deallocateSecondary(BackendPtr);
}
// Internal quarantine allocation and deallocation functions. We first check
// that the batches are indeed serviced by the Primary.
// TODO(kostyak): figure out the best way to protect the batches.
void *Allocate(uptr Size) {
const uptr BatchClassId = SizeClassMap::ClassID(sizeof(QuarantineBatch));
return getBackend().allocatePrimary(Cache_, BatchClassId);
}
void Deallocate(void *Ptr) {
const uptr BatchClassId = SizeClassMap::ClassID(sizeof(QuarantineBatch));
getBackend().deallocatePrimary(Cache_, Ptr, BatchClassId);
}
AllocatorCacheT *Cache_;
COMPILER_CHECK(sizeof(QuarantineBatch) < SizeClassMap::kMaxSize);
};
typedef Quarantine<QuarantineCallback, void> QuarantineT;
typedef QuarantineT::Cache QuarantineCacheT;
COMPILER_CHECK(sizeof(QuarantineCacheT) <=
sizeof(ScudoTSD::QuarantineCachePlaceHolder));
QuarantineCacheT *getQuarantineCache(ScudoTSD *TSD) {
return reinterpret_cast<QuarantineCacheT *>(TSD->QuarantineCachePlaceHolder);
}
#ifdef GWP_ASAN_HOOKS
static gwp_asan::GuardedPoolAllocator GuardedAlloc;
#endif // GWP_ASAN_HOOKS
struct Allocator {
static const uptr MaxAllowedMallocSize =
FIRST_32_SECOND_64(2UL << 30, 1ULL << 40);
BackendT Backend;
QuarantineT Quarantine;
u32 QuarantineChunksUpToSize;
bool DeallocationTypeMismatch;
bool ZeroContents;
bool DeleteSizeMismatch;
bool CheckRssLimit;
uptr HardRssLimitMb;
uptr SoftRssLimitMb;
atomic_uint8_t RssLimitExceeded;
atomic_uint64_t RssLastCheckedAtNS;
explicit Allocator(LinkerInitialized)
: Quarantine(LINKER_INITIALIZED) {}
NOINLINE void performSanityChecks();
void init() {
SanitizerToolName = "Scudo";
PrimaryAllocatorName = "ScudoPrimary";
SecondaryAllocatorName = "ScudoSecondary";
initFlags();
performSanityChecks();
// Check if hardware CRC32 is supported in the binary and by the platform,
// if so, opt for the CRC32 hardware version of the checksum.
if (&computeHardwareCRC32 && hasHardwareCRC32())
atomic_store_relaxed(&HashAlgorithm, CRC32Hardware);
SetAllocatorMayReturnNull(common_flags()->allocator_may_return_null);
Backend.init(common_flags()->allocator_release_to_os_interval_ms);
HardRssLimitMb = common_flags()->hard_rss_limit_mb;
SoftRssLimitMb = common_flags()->soft_rss_limit_mb;
Quarantine.Init(
static_cast<uptr>(getFlags()->QuarantineSizeKb) << 10,
static_cast<uptr>(getFlags()->ThreadLocalQuarantineSizeKb) << 10);
QuarantineChunksUpToSize = (Quarantine.GetCacheSize() == 0) ? 0 :
getFlags()->QuarantineChunksUpToSize;
DeallocationTypeMismatch = getFlags()->DeallocationTypeMismatch;
DeleteSizeMismatch = getFlags()->DeleteSizeMismatch;
ZeroContents = getFlags()->ZeroContents;
if (UNLIKELY(!GetRandom(reinterpret_cast<void *>(&Cookie), sizeof(Cookie),
/*blocking=*/false))) {
Cookie = static_cast<u32>((NanoTime() >> 12) ^
(reinterpret_cast<uptr>(this) >> 4));
}
CheckRssLimit = HardRssLimitMb || SoftRssLimitMb;
if (CheckRssLimit)
atomic_store_relaxed(&RssLastCheckedAtNS, MonotonicNanoTime());
}
// Helper function that checks for a valid Scudo chunk. nullptr isn't.
bool isValidPointer(const void *Ptr) {
initThreadMaybe();
if (UNLIKELY(!Ptr))
return false;
if (!Chunk::isAligned(Ptr))
return false;
return Chunk::isValid(Ptr);
}
NOINLINE bool isRssLimitExceeded();
// Allocates a chunk.
void *allocate(uptr Size, uptr Alignment, AllocType Type,
bool ForceZeroContents = false) {
initThreadMaybe();
#ifdef GWP_ASAN_HOOKS
if (UNLIKELY(GuardedAlloc.shouldSample())) {
if (void *Ptr = GuardedAlloc.allocate(Size))
return Ptr;
}
#endif // GWP_ASAN_HOOKS
if (UNLIKELY(Alignment > MaxAlignment)) {
if (AllocatorMayReturnNull())
return nullptr;
reportAllocationAlignmentTooBig(Alignment, MaxAlignment);
}
if (UNLIKELY(Alignment < MinAlignment))
Alignment = MinAlignment;
const uptr NeededSize = RoundUpTo(Size ? Size : 1, MinAlignment) +
Chunk::getHeaderSize();
const uptr AlignedSize = (Alignment > MinAlignment) ?
NeededSize + (Alignment - Chunk::getHeaderSize()) : NeededSize;
if (UNLIKELY(Size >= MaxAllowedMallocSize) ||
UNLIKELY(AlignedSize >= MaxAllowedMallocSize)) {
if (AllocatorMayReturnNull())
return nullptr;
reportAllocationSizeTooBig(Size, AlignedSize, MaxAllowedMallocSize);
}
if (CheckRssLimit && UNLIKELY(isRssLimitExceeded())) {
if (AllocatorMayReturnNull())
return nullptr;
reportRssLimitExceeded();
}
// Primary and Secondary backed allocations have a different treatment. We
// deal with alignment requirements of Primary serviced allocations here,
// but the Secondary will take care of its own alignment needs.
void *BackendPtr;
uptr BackendSize;
u8 ClassId;
if (PrimaryT::CanAllocate(AlignedSize, MinAlignment)) {
BackendSize = AlignedSize;
ClassId = SizeClassMap::ClassID(BackendSize);
bool UnlockRequired;
ScudoTSD *TSD = getTSDAndLock(&UnlockRequired);
BackendPtr = Backend.allocatePrimary(&TSD->Cache, ClassId);
if (UnlockRequired)
TSD->unlock();
} else {
BackendSize = NeededSize;
ClassId = 0;
BackendPtr = Backend.allocateSecondary(BackendSize, Alignment);
}
if (UNLIKELY(!BackendPtr)) {
SetAllocatorOutOfMemory();
if (AllocatorMayReturnNull())
return nullptr;
reportOutOfMemory(Size);
}
// If requested, we will zero out the entire contents of the returned chunk.
if ((ForceZeroContents || ZeroContents) && ClassId)
memset(BackendPtr, 0, PrimaryT::ClassIdToSize(ClassId));
UnpackedHeader Header = {};
uptr UserPtr = reinterpret_cast<uptr>(BackendPtr) + Chunk::getHeaderSize();
if (UNLIKELY(!IsAligned(UserPtr, Alignment))) {
// Since the Secondary takes care of alignment, a non-aligned pointer
// means it is from the Primary. It is also the only case where the offset
// field of the header would be non-zero.
DCHECK(ClassId);
const uptr AlignedUserPtr = RoundUpTo(UserPtr, Alignment);
Header.Offset = (AlignedUserPtr - UserPtr) >> MinAlignmentLog;
UserPtr = AlignedUserPtr;
}
DCHECK_LE(UserPtr + Size, reinterpret_cast<uptr>(BackendPtr) + BackendSize);
Header.State = ChunkAllocated;
Header.AllocType = Type;
if (ClassId) {
Header.ClassId = ClassId;
Header.SizeOrUnusedBytes = Size;
} else {
// The secondary fits the allocations to a page, so the amount of unused
// bytes is the difference between the end of the user allocation and the
// next page boundary.
const uptr PageSize = GetPageSizeCached();
const uptr TrailingBytes = (UserPtr + Size) & (PageSize - 1);
if (TrailingBytes)
Header.SizeOrUnusedBytes = PageSize - TrailingBytes;
}
void *Ptr = reinterpret_cast<void *>(UserPtr);
Chunk::storeHeader(Ptr, &Header);
if (SCUDO_CAN_USE_HOOKS && &__sanitizer_malloc_hook)
__sanitizer_malloc_hook(Ptr, Size);
return Ptr;
}
// Place a chunk in the quarantine or directly deallocate it in the event of
// a zero-sized quarantine, or if the size of the chunk is greater than the
// quarantine chunk size threshold.
void quarantineOrDeallocateChunk(void *Ptr, UnpackedHeader *Header,
uptr Size) {
const bool BypassQuarantine = !Size || (Size > QuarantineChunksUpToSize);
if (BypassQuarantine) {
UnpackedHeader NewHeader = *Header;
NewHeader.State = ChunkAvailable;
Chunk::compareExchangeHeader(Ptr, &NewHeader, Header);
void *BackendPtr = Chunk::getBackendPtr(Ptr, Header);
if (Header->ClassId) {
bool UnlockRequired;
ScudoTSD *TSD = getTSDAndLock(&UnlockRequired);
getBackend().deallocatePrimary(&TSD->Cache, BackendPtr,
Header->ClassId);
if (UnlockRequired)
TSD->unlock();
} else {
getBackend().deallocateSecondary(BackendPtr);
}
} else {
// If a small memory amount was allocated with a larger alignment, we want
// to take that into account. Otherwise the Quarantine would be filled
// with tiny chunks, taking a lot of VA memory. This is an approximation
// of the usable size, that allows us to not call
// GetActuallyAllocatedSize.
const uptr EstimatedSize = Size + (Header->Offset << MinAlignmentLog);
UnpackedHeader NewHeader = *Header;
NewHeader.State = ChunkQuarantine;
Chunk::compareExchangeHeader(Ptr, &NewHeader, Header);
bool UnlockRequired;
ScudoTSD *TSD = getTSDAndLock(&UnlockRequired);
Quarantine.Put(getQuarantineCache(TSD), QuarantineCallback(&TSD->Cache),
Ptr, EstimatedSize);
if (UnlockRequired)
TSD->unlock();
}
}
// Deallocates a Chunk, which means either adding it to the quarantine or
// directly returning it to the backend if criteria are met.
void deallocate(void *Ptr, uptr DeleteSize, uptr DeleteAlignment,
AllocType Type) {
// For a deallocation, we only ensure minimal initialization, meaning thread
// local data will be left uninitialized for now (when using ELF TLS). The
// fallback cache will be used instead. This is a workaround for a situation
// where the only heap operation performed in a thread would be a free past
// the TLS destructors, ending up in initialized thread specific data never
// being destroyed properly. Any other heap operation will do a full init.
initThreadMaybe(/*MinimalInit=*/true);
if (SCUDO_CAN_USE_HOOKS && &__sanitizer_free_hook)
__sanitizer_free_hook(Ptr);
if (UNLIKELY(!Ptr))
return;
#ifdef GWP_ASAN_HOOKS
if (UNLIKELY(GuardedAlloc.pointerIsMine(Ptr))) {
GuardedAlloc.deallocate(Ptr);
return;
}
#endif // GWP_ASAN_HOOKS
if (UNLIKELY(!Chunk::isAligned(Ptr)))
dieWithMessage("misaligned pointer when deallocating address %p\n", Ptr);
UnpackedHeader Header;
Chunk::loadHeader(Ptr, &Header);
if (UNLIKELY(Header.State != ChunkAllocated))
dieWithMessage("invalid chunk state when deallocating address %p\n", Ptr);
if (DeallocationTypeMismatch) {
// The deallocation type has to match the allocation one.
if (Header.AllocType != Type) {
// With the exception of memalign'd Chunks, that can be still be free'd.
if (Header.AllocType != FromMemalign || Type != FromMalloc)
dieWithMessage("allocation type mismatch when deallocating address "
"%p\n", Ptr);
}
}
const uptr Size = Chunk::getSize(Ptr, &Header);
if (DeleteSizeMismatch) {
if (DeleteSize && DeleteSize != Size)
dieWithMessage("invalid sized delete when deallocating address %p\n",
Ptr);
}
(void)DeleteAlignment; // TODO(kostyak): verify that the alignment matches.
quarantineOrDeallocateChunk(Ptr, &Header, Size);
}
// Reallocates a chunk. We can save on a new allocation if the new requested
// size still fits in the chunk.
void *reallocate(void *OldPtr, uptr NewSize) {
initThreadMaybe();
#ifdef GWP_ASAN_HOOKS
if (UNLIKELY(GuardedAlloc.pointerIsMine(OldPtr))) {
size_t OldSize = GuardedAlloc.getSize(OldPtr);
void *NewPtr = allocate(NewSize, MinAlignment, FromMalloc);
if (NewPtr)
memcpy(NewPtr, OldPtr, (NewSize < OldSize) ? NewSize : OldSize);
GuardedAlloc.deallocate(OldPtr);
return NewPtr;
}
#endif // GWP_ASAN_HOOKS
if (UNLIKELY(!Chunk::isAligned(OldPtr)))
dieWithMessage("misaligned address when reallocating address %p\n",
OldPtr);
UnpackedHeader OldHeader;
Chunk::loadHeader(OldPtr, &OldHeader);
if (UNLIKELY(OldHeader.State != ChunkAllocated))
dieWithMessage("invalid chunk state when reallocating address %p\n",
OldPtr);
if (DeallocationTypeMismatch) {
if (UNLIKELY(OldHeader.AllocType != FromMalloc))
dieWithMessage("allocation type mismatch when reallocating address "
"%p\n", OldPtr);
}
const uptr UsableSize = Chunk::getUsableSize(OldPtr, &OldHeader);
// The new size still fits in the current chunk, and the size difference
// is reasonable.
if (NewSize <= UsableSize &&
(UsableSize - NewSize) < (SizeClassMap::kMaxSize / 2)) {
UnpackedHeader NewHeader = OldHeader;
NewHeader.SizeOrUnusedBytes =
OldHeader.ClassId ? NewSize : UsableSize - NewSize;
Chunk::compareExchangeHeader(OldPtr, &NewHeader, &OldHeader);
return OldPtr;
}
// Otherwise, we have to allocate a new chunk and copy the contents of the
// old one.
void *NewPtr = allocate(NewSize, MinAlignment, FromMalloc);
if (NewPtr) {
const uptr OldSize = OldHeader.ClassId ? OldHeader.SizeOrUnusedBytes :
UsableSize - OldHeader.SizeOrUnusedBytes;
memcpy(NewPtr, OldPtr, Min(NewSize, UsableSize));
quarantineOrDeallocateChunk(OldPtr, &OldHeader, OldSize);
}
return NewPtr;
}
// Helper function that returns the actual usable size of a chunk.
uptr getUsableSize(const void *Ptr) {
initThreadMaybe();
if (UNLIKELY(!Ptr))
return 0;
#ifdef GWP_ASAN_HOOKS
if (UNLIKELY(GuardedAlloc.pointerIsMine(Ptr)))
return GuardedAlloc.getSize(Ptr);
#endif // GWP_ASAN_HOOKS
UnpackedHeader Header;
Chunk::loadHeader(Ptr, &Header);
// Getting the usable size of a chunk only makes sense if it's allocated.
if (UNLIKELY(Header.State != ChunkAllocated))
dieWithMessage("invalid chunk state when sizing address %p\n", Ptr);
return Chunk::getUsableSize(Ptr, &Header);
}
void *calloc(uptr NMemB, uptr Size) {
initThreadMaybe();
if (UNLIKELY(CheckForCallocOverflow(NMemB, Size))) {
if (AllocatorMayReturnNull())
return nullptr;
reportCallocOverflow(NMemB, Size);
}
return allocate(NMemB * Size, MinAlignment, FromMalloc, true);
}
void commitBack(ScudoTSD *TSD) {
Quarantine.Drain(getQuarantineCache(TSD), QuarantineCallback(&TSD->Cache));
Backend.destroyCache(&TSD->Cache);
}
uptr getStats(AllocatorStat StatType) {
initThreadMaybe();
uptr stats[AllocatorStatCount];
Backend.getStats(stats);
return stats[StatType];
}
bool canReturnNull() {
initThreadMaybe();
return AllocatorMayReturnNull();
}
void setRssLimit(uptr LimitMb, bool HardLimit) {
if (HardLimit)
HardRssLimitMb = LimitMb;
else
SoftRssLimitMb = LimitMb;
CheckRssLimit = HardRssLimitMb || SoftRssLimitMb;
}
void printStats() {
initThreadMaybe();
Backend.printStats();
}
};
NOINLINE void Allocator::performSanityChecks() {
// Verify that the header offset field can hold the maximum offset. In the
// case of the Secondary allocator, it takes care of alignment and the
// offset will always be 0. In the case of the Primary, the worst case
// scenario happens in the last size class, when the backend allocation
// would already be aligned on the requested alignment, which would happen
// to be the maximum alignment that would fit in that size class. As a
// result, the maximum offset will be at most the maximum alignment for the
// last size class minus the header size, in multiples of MinAlignment.
UnpackedHeader Header = {};
const uptr MaxPrimaryAlignment =
1 << MostSignificantSetBitIndex(SizeClassMap::kMaxSize - MinAlignment);
const uptr MaxOffset =
(MaxPrimaryAlignment - Chunk::getHeaderSize()) >> MinAlignmentLog;
Header.Offset = MaxOffset;
if (Header.Offset != MaxOffset)
dieWithMessage("maximum possible offset doesn't fit in header\n");
// Verify that we can fit the maximum size or amount of unused bytes in the
// header. Given that the Secondary fits the allocation to a page, the worst
// case scenario happens in the Primary. It will depend on the second to
// last and last class sizes, as well as the dynamic base for the Primary.
// The following is an over-approximation that works for our needs.
const uptr MaxSizeOrUnusedBytes = SizeClassMap::kMaxSize - 1;
Header.SizeOrUnusedBytes = MaxSizeOrUnusedBytes;
if (Header.SizeOrUnusedBytes != MaxSizeOrUnusedBytes)
dieWithMessage("maximum possible unused bytes doesn't fit in header\n");
const uptr LargestClassId = SizeClassMap::kLargestClassID;
Header.ClassId = LargestClassId;
if (Header.ClassId != LargestClassId)
dieWithMessage("largest class ID doesn't fit in header\n");
}
// Opportunistic RSS limit check. This will update the RSS limit status, if
// it can, every 250ms, otherwise it will just return the current one.
NOINLINE bool Allocator::isRssLimitExceeded() {
u64 LastCheck = atomic_load_relaxed(&RssLastCheckedAtNS);
const u64 CurrentCheck = MonotonicNanoTime();
if (LIKELY(CurrentCheck < LastCheck + (250ULL * 1000000ULL)))
return atomic_load_relaxed(&RssLimitExceeded);
if (!atomic_compare_exchange_weak(&RssLastCheckedAtNS, &LastCheck,
CurrentCheck, memory_order_relaxed))
return atomic_load_relaxed(&RssLimitExceeded);
// TODO(kostyak): We currently use sanitizer_common's GetRSS which reads the
// RSS from /proc/self/statm by default. We might want to
// call getrusage directly, even if it's less accurate.
const uptr CurrentRssMb = GetRSS() >> 20;
if (HardRssLimitMb && UNLIKELY(HardRssLimitMb < CurrentRssMb))
dieWithMessage("hard RSS limit exhausted (%zdMb vs %zdMb)\n",
HardRssLimitMb, CurrentRssMb);
if (SoftRssLimitMb) {
if (atomic_load_relaxed(&RssLimitExceeded)) {
if (CurrentRssMb <= SoftRssLimitMb)
atomic_store_relaxed(&RssLimitExceeded, false);
} else {
if (CurrentRssMb > SoftRssLimitMb) {
atomic_store_relaxed(&RssLimitExceeded, true);
Printf("Scudo INFO: soft RSS limit exhausted (%zdMb vs %zdMb)\n",
SoftRssLimitMb, CurrentRssMb);
}
}
}
return atomic_load_relaxed(&RssLimitExceeded);
}
static Allocator Instance(LINKER_INITIALIZED);
static BackendT &getBackend() {
return Instance.Backend;
}
void initScudo() {
Instance.init();
#ifdef GWP_ASAN_HOOKS
gwp_asan::options::initOptions();
gwp_asan::options::Options &Opts = gwp_asan::options::getOptions();
Opts.Backtrace = gwp_asan::options::getBacktraceFunction();
GuardedAlloc.init(Opts);
if (Opts.InstallSignalHandlers)
gwp_asan::crash_handler::installSignalHandlers(
&GuardedAlloc, __sanitizer::Printf,
gwp_asan::options::getPrintBacktraceFunction(), Opts.Backtrace);
#endif // GWP_ASAN_HOOKS
}
void ScudoTSD::init() {
getBackend().initCache(&Cache);
memset(QuarantineCachePlaceHolder, 0, sizeof(QuarantineCachePlaceHolder));
}
void ScudoTSD::commitBack() {
Instance.commitBack(this);
}
void *scudoAllocate(uptr Size, uptr Alignment, AllocType Type) {
if (Alignment && UNLIKELY(!IsPowerOfTwo(Alignment))) {
errno = EINVAL;
if (Instance.canReturnNull())
return nullptr;
reportAllocationAlignmentNotPowerOfTwo(Alignment);
}
return SetErrnoOnNull(Instance.allocate(Size, Alignment, Type));
}
void scudoDeallocate(void *Ptr, uptr Size, uptr Alignment, AllocType Type) {
Instance.deallocate(Ptr, Size, Alignment, Type);
}
void *scudoRealloc(void *Ptr, uptr Size) {
if (!Ptr)
return SetErrnoOnNull(Instance.allocate(Size, MinAlignment, FromMalloc));
if (Size == 0) {
Instance.deallocate(Ptr, 0, 0, FromMalloc);
return nullptr;
}
return SetErrnoOnNull(Instance.reallocate(Ptr, Size));
}
void *scudoCalloc(uptr NMemB, uptr Size) {
return SetErrnoOnNull(Instance.calloc(NMemB, Size));
}
void *scudoValloc(uptr Size) {
return SetErrnoOnNull(
Instance.allocate(Size, GetPageSizeCached(), FromMemalign));
}
void *scudoPvalloc(uptr Size) {
const uptr PageSize = GetPageSizeCached();
if (UNLIKELY(CheckForPvallocOverflow(Size, PageSize))) {
errno = ENOMEM;
if (Instance.canReturnNull())
return nullptr;
reportPvallocOverflow(Size);
}
// pvalloc(0) should allocate one page.
Size = Size ? RoundUpTo(Size, PageSize) : PageSize;
return SetErrnoOnNull(Instance.allocate(Size, PageSize, FromMemalign));
}
int scudoPosixMemalign(void **MemPtr, uptr Alignment, uptr Size) {
if (UNLIKELY(!CheckPosixMemalignAlignment(Alignment))) {
if (!Instance.canReturnNull())
reportInvalidPosixMemalignAlignment(Alignment);
return EINVAL;
}
void *Ptr = Instance.allocate(Size, Alignment, FromMemalign);
if (UNLIKELY(!Ptr))
return ENOMEM;
*MemPtr = Ptr;
return 0;
}
void *scudoAlignedAlloc(uptr Alignment, uptr Size) {
if (UNLIKELY(!CheckAlignedAllocAlignmentAndSize(Alignment, Size))) {
errno = EINVAL;
if (Instance.canReturnNull())
return nullptr;
reportInvalidAlignedAllocAlignment(Size, Alignment);
}
return SetErrnoOnNull(Instance.allocate(Size, Alignment, FromMalloc));
}
uptr scudoMallocUsableSize(void *Ptr) {
return Instance.getUsableSize(Ptr);
}
} // namespace __scudo
using namespace __scudo;
// MallocExtension helper functions
uptr __sanitizer_get_current_allocated_bytes() {
return Instance.getStats(AllocatorStatAllocated);
}
uptr __sanitizer_get_heap_size() {
return Instance.getStats(AllocatorStatMapped);
}
uptr __sanitizer_get_free_bytes() {
return 1;
}
uptr __sanitizer_get_unmapped_bytes() {
return 1;
}
uptr __sanitizer_get_estimated_allocated_size(uptr Size) {
return Size;
}
int __sanitizer_get_ownership(const void *Ptr) {
return Instance.isValidPointer(Ptr);
}
uptr __sanitizer_get_allocated_size(const void *Ptr) {
return Instance.getUsableSize(Ptr);
}
#if !SANITIZER_SUPPORTS_WEAK_HOOKS
SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_malloc_hook,
void *Ptr, uptr Size) {
(void)Ptr;
(void)Size;
}
SANITIZER_INTERFACE_WEAK_DEF(void, __sanitizer_free_hook, void *Ptr) {
(void)Ptr;
}
#endif
// Interface functions
void __scudo_set_rss_limit(uptr LimitMb, s32 HardLimit) {
if (!SCUDO_CAN_USE_PUBLIC_INTERFACE)
return;
Instance.setRssLimit(LimitMb, !!HardLimit);
}
void __scudo_print_stats() {
Instance.printStats();
}
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