Add clang20-rt into ydb sync config

commit_hash:a644e6487e802adc4b59a62ef53000053f586377

1 files changed, 472 insertions, 0 deletions

diff --git a/contrib/libs/clang20-rt/lib/gwp_asan/guarded_pool_allocator.cpp b/contrib/libs/clang20-rt/lib/gwp_asan/guarded_pool_allocator.cpp
new file mode 100644
index 00000000000..a5f1ecd4b26
--- /dev/null
+++ b/contrib/libs/clang20-rt/lib/gwp_asan/guarded_pool_allocator.cpp
@@ -0,0 +1,472 @@
+//===-- guarded_pool_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
+//
+//===----------------------------------------------------------------------===//
+
+#include "gwp_asan/guarded_pool_allocator.h"
+
+#include "gwp_asan/crash_handler.h"
+#include "gwp_asan/options.h"
+#include "gwp_asan/utilities.h"
+
+#include <assert.h>
+#include <stddef.h>
+
+using AllocationMetadata = gwp_asan::AllocationMetadata;
+using Error = gwp_asan::Error;
+
+namespace gwp_asan {
+namespace {
+// Forward declare the pointer to the singleton version of this class.
+// Instantiated during initialisation, this allows the signal handler
+// to find this class in order to deduce the root cause of failures. Must not be
+// referenced by users outside this translation unit, in order to avoid
+// init-order-fiasco.
+GuardedPoolAllocator *SingletonPtr = nullptr;
+
+size_t roundUpTo(size_t Size, size_t Boundary) {
+  return (Size + Boundary - 1) & ~(Boundary - 1);
+}
+
+uintptr_t getPageAddr(uintptr_t Ptr, uintptr_t PageSize) {
+  return Ptr & ~(PageSize - 1);
+}
+
+bool isPowerOfTwo(uintptr_t X) { return (X & (X - 1)) == 0; }
+} // anonymous namespace
+
+// Gets the singleton implementation of this class. Thread-compatible until
+// init() is called, thread-safe afterwards.
+GuardedPoolAllocator *GuardedPoolAllocator::getSingleton() {
+  return SingletonPtr;
+}
+
+void GuardedPoolAllocator::init(const options::Options &Opts) {
+  // Note: We return from the constructor here if GWP-ASan is not available.
+  // This will stop heap-allocation of class members, as well as mmap() of the
+  // guarded slots.
+  if (!Opts.Enabled || Opts.SampleRate == 0 ||
+      Opts.MaxSimultaneousAllocations == 0)
+    return;
+
+  check(Opts.SampleRate >= 0, "GWP-ASan Error: SampleRate is < 0.");
+  check(Opts.SampleRate < (1 << 30), "GWP-ASan Error: SampleRate is >= 2^30.");
+  check(Opts.MaxSimultaneousAllocations >= 0,
+        "GWP-ASan Error: MaxSimultaneousAllocations is < 0.");
+
+  check(SingletonPtr == nullptr,
+        "There's already a live GuardedPoolAllocator!");
+  SingletonPtr = this;
+  Backtrace = Opts.Backtrace;
+
+  State.VersionMagic = {{AllocatorVersionMagic::kAllocatorVersionMagic[0],
+                         AllocatorVersionMagic::kAllocatorVersionMagic[1],
+                         AllocatorVersionMagic::kAllocatorVersionMagic[2],
+                         AllocatorVersionMagic::kAllocatorVersionMagic[3]},
+                        AllocatorVersionMagic::kAllocatorVersion,
+                        0};
+
+  State.MaxSimultaneousAllocations = Opts.MaxSimultaneousAllocations;
+
+  const size_t PageSize = getPlatformPageSize();
+  // getPageAddr() and roundUpTo() assume the page size to be a power of 2.
+  assert((PageSize & (PageSize - 1)) == 0);
+  State.PageSize = PageSize;
+
+  // Number of pages required =
+  //  + MaxSimultaneousAllocations * maximumAllocationSize (N pages per slot)
+  //  + MaxSimultaneousAllocations (one guard on the left side of each slot)
+  //  + 1 (an extra guard page at the end of the pool, on the right side)
+  //  + 1 (an extra page that's used for reporting internally-detected crashes,
+  //       like double free and invalid free, to the signal handler; see
+  //       raiseInternallyDetectedError() for more info)
+  size_t PoolBytesRequired =
+      PageSize * (2 + State.MaxSimultaneousAllocations) +
+      State.MaxSimultaneousAllocations * State.maximumAllocationSize();
+  assert(PoolBytesRequired % PageSize == 0);
+  void *GuardedPoolMemory = reserveGuardedPool(PoolBytesRequired);
+
+  size_t BytesRequired =
+      roundUpTo(State.MaxSimultaneousAllocations * sizeof(*Metadata), PageSize);
+  Metadata = reinterpret_cast<AllocationMetadata *>(
+      map(BytesRequired, kGwpAsanMetadataName));
+
+  // Allocate memory and set up the free pages queue.
+  BytesRequired = roundUpTo(
+      State.MaxSimultaneousAllocations * sizeof(*FreeSlots), PageSize);
+  FreeSlots =
+      reinterpret_cast<size_t *>(map(BytesRequired, kGwpAsanFreeSlotsName));
+
+  // Multiply the sample rate by 2 to give a good, fast approximation for (1 /
+  // SampleRate) chance of sampling.
+  if (Opts.SampleRate != 1)
+    AdjustedSampleRatePlusOne = static_cast<uint32_t>(Opts.SampleRate) * 2 + 1;
+  else
+    AdjustedSampleRatePlusOne = 2;
+
+  initPRNG();
+  getThreadLocals()->NextSampleCounter =
+      ((getRandomUnsigned32() % (AdjustedSampleRatePlusOne - 1)) + 1) &
+      ThreadLocalPackedVariables::NextSampleCounterMask;
+
+  State.GuardedPagePool = reinterpret_cast<uintptr_t>(GuardedPoolMemory);
+  State.GuardedPagePoolEnd =
+      reinterpret_cast<uintptr_t>(GuardedPoolMemory) + PoolBytesRequired;
+
+  if (Opts.InstallForkHandlers)
+    installAtFork();
+}
+
+void GuardedPoolAllocator::disable() {
+  PoolMutex.lock();
+  BacktraceMutex.lock();
+}
+
+void GuardedPoolAllocator::enable() {
+  PoolMutex.unlock();
+  BacktraceMutex.unlock();
+}
+
+void GuardedPoolAllocator::iterate(void *Base, size_t Size, iterate_callback Cb,
+                                   void *Arg) {
+  uintptr_t Start = reinterpret_cast<uintptr_t>(Base);
+  for (size_t i = 0; i < State.MaxSimultaneousAllocations; ++i) {
+    const AllocationMetadata &Meta = Metadata[i];
+    if (Meta.Addr && !Meta.IsDeallocated && Meta.Addr >= Start &&
+        Meta.Addr < Start + Size)
+      Cb(Meta.Addr, Meta.RequestedSize, Arg);
+  }
+}
+
+void GuardedPoolAllocator::uninitTestOnly() {
+  if (State.GuardedPagePool) {
+    unreserveGuardedPool();
+    State.GuardedPagePool = 0;
+    State.GuardedPagePoolEnd = 0;
+  }
+  if (Metadata) {
+    unmap(Metadata,
+          roundUpTo(State.MaxSimultaneousAllocations * sizeof(*Metadata),
+                    State.PageSize));
+    Metadata = nullptr;
+  }
+  if (FreeSlots) {
+    unmap(FreeSlots,
+          roundUpTo(State.MaxSimultaneousAllocations * sizeof(*FreeSlots),
+                    State.PageSize));
+    FreeSlots = nullptr;
+  }
+  *getThreadLocals() = ThreadLocalPackedVariables();
+  SingletonPtr = nullptr;
+}
+
+// Note, minimum backing allocation size in GWP-ASan is always one page, and
+// each slot could potentially be multiple pages (but always in
+// page-increments). Thus, for anything that requires less than page size
+// alignment, we don't need to allocate extra padding to ensure the alignment
+// can be met.
+size_t GuardedPoolAllocator::getRequiredBackingSize(size_t Size,
+                                                    size_t Alignment,
+                                                    size_t PageSize) {
+  assert(isPowerOfTwo(Alignment) && "Alignment must be a power of two!");
+  assert(Alignment != 0 && "Alignment should be non-zero");
+  assert(Size != 0 && "Size should be non-zero");
+
+  if (Alignment <= PageSize)
+    return Size;
+
+  return Size + Alignment - PageSize;
+}
+
+uintptr_t GuardedPoolAllocator::alignUp(uintptr_t Ptr, size_t Alignment) {
+  assert(isPowerOfTwo(Alignment) && "Alignment must be a power of two!");
+  assert(Alignment != 0 && "Alignment should be non-zero");
+  if ((Ptr & (Alignment - 1)) == 0)
+    return Ptr;
+
+  Ptr += Alignment - (Ptr & (Alignment - 1));
+  return Ptr;
+}
+
+uintptr_t GuardedPoolAllocator::alignDown(uintptr_t Ptr, size_t Alignment) {
+  assert(isPowerOfTwo(Alignment) && "Alignment must be a power of two!");
+  assert(Alignment != 0 && "Alignment should be non-zero");
+  if ((Ptr & (Alignment - 1)) == 0)
+    return Ptr;
+
+  Ptr -= Ptr & (Alignment - 1);
+  return Ptr;
+}
+
+void *GuardedPoolAllocator::allocate(size_t Size, size_t Alignment) {
+  // GuardedPagePoolEnd == 0 when GWP-ASan is disabled. If we are disabled, fall
+  // back to the supporting allocator.
+  if (State.GuardedPagePoolEnd == 0) {
+    getThreadLocals()->NextSampleCounter =
+        (AdjustedSampleRatePlusOne - 1) &
+        ThreadLocalPackedVariables::NextSampleCounterMask;
+    return nullptr;
+  }
+
+  if (Size == 0)
+    Size = 1;
+  if (Alignment == 0)
+    Alignment = alignof(max_align_t);
+
+  if (!isPowerOfTwo(Alignment) || Alignment > State.maximumAllocationSize() ||
+      Size > State.maximumAllocationSize())
+    return nullptr;
+
+  size_t BackingSize = getRequiredBackingSize(Size, Alignment, State.PageSize);
+  if (BackingSize > State.maximumAllocationSize())
+    return nullptr;
+
+  // Protect against recursivity.
+  if (getThreadLocals()->RecursiveGuard)
+    return nullptr;
+  ScopedRecursiveGuard SRG;
+
+  size_t Index;
+  {
+    ScopedLock L(PoolMutex);
+    Index = reserveSlot();
+  }
+
+  if (Index == kInvalidSlotID)
+    return nullptr;
+
+  uintptr_t SlotStart = State.slotToAddr(Index);
+  AllocationMetadata *Meta = addrToMetadata(SlotStart);
+  uintptr_t SlotEnd = State.slotToAddr(Index) + State.maximumAllocationSize();
+  uintptr_t UserPtr;
+  // Randomly choose whether to left-align or right-align the allocation, and
+  // then apply the necessary adjustments to get an aligned pointer.
+  if (getRandomUnsigned32() % 2 == 0)
+    UserPtr = alignUp(SlotStart, Alignment);
+  else
+    UserPtr = alignDown(SlotEnd - Size, Alignment);
+
+  assert(UserPtr >= SlotStart);
+  assert(UserPtr + Size <= SlotEnd);
+
+  // If a slot is multiple pages in size, and the allocation takes up a single
+  // page, we can improve overflow detection by leaving the unused pages as
+  // unmapped.
+  const size_t PageSize = State.PageSize;
+  allocateInGuardedPool(
+      reinterpret_cast<void *>(getPageAddr(UserPtr, PageSize)),
+      roundUpTo(Size, PageSize));
+
+  Meta->RecordAllocation(UserPtr, Size);
+  {
+    ScopedLock UL(BacktraceMutex);
+    Meta->AllocationTrace.RecordBacktrace(Backtrace);
+  }
+
+  return reinterpret_cast<void *>(UserPtr);
+}
+
+void GuardedPoolAllocator::raiseInternallyDetectedError(uintptr_t Address,
+                                                        Error E) {
+  // Disable the allocator before setting the internal failure state. In
+  // non-recoverable mode, the allocator will be permanently disabled, and so
+  // things will be accessed without locks.
+  disable();
+
+  // Races between internally- and externally-raised faults can happen. Right
+  // now, in this thread we've locked the allocator in order to raise an
+  // internally-detected fault, and another thread could SIGSEGV to raise an
+  // externally-detected fault. What will happen is that the other thread will
+  // wait in the signal handler, as we hold the allocator's locks from the
+  // disable() above. We'll trigger the signal handler by touching the
+  // internal-signal-raising address below, and the signal handler from our
+  // thread will get to run first as we will continue to hold the allocator
+  // locks until the enable() at the end of this function. Be careful though, if
+  // this thread receives another SIGSEGV after the disable() above, but before
+  // touching the internal-signal-raising address below, then this thread will
+  // get an "externally-raised" SIGSEGV while *also* holding the allocator
+  // locks, which means this thread's signal handler will deadlock. This could
+  // be resolved with a re-entrant lock, but asking platforms to implement this
+  // seems unnecessary given the only way to get a SIGSEGV in this critical
+  // section is either a memory safety bug in the couple lines of code below (be
+  // careful!), or someone outside uses `kill(this_thread, SIGSEGV)`, which
+  // really shouldn't happen.
+
+  State.FailureType = E;
+  State.FailureAddress = Address;
+
+  // Raise a SEGV by touching a specific address that identifies to the crash
+  // handler that this is an internally-raised fault. Changing this address?
+  // Don't forget to update __gwp_asan_get_internal_crash_address.
+  volatile char *p =
+      reinterpret_cast<char *>(State.internallyDetectedErrorFaultAddress());
+  *p = 0;
+
+  // This should never be reached in non-recoverable mode. Ensure that the
+  // signal handler called handleRecoverablePostCrashReport(), which was
+  // responsible for re-setting these fields.
+  assert(State.FailureType == Error::UNKNOWN);
+  assert(State.FailureAddress == 0u);
+
+  // In recoverable mode, the signal handler (after dumping the crash) marked
+  // the page containing the InternalFaultSegvAddress as read/writeable, to
+  // allow the second touch to succeed after returning from the signal handler.
+  // Now, we need to mark the page as non-read/write-able again, so future
+  // internal faults can be raised.
+  deallocateInGuardedPool(
+      reinterpret_cast<void *>(getPageAddr(
+          State.internallyDetectedErrorFaultAddress(), State.PageSize)),
+      State.PageSize);
+
+  // And now we're done with patching ourselves back up, enable the allocator.
+  enable();
+}
+
+void GuardedPoolAllocator::deallocate(void *Ptr) {
+  assert(pointerIsMine(Ptr) && "Pointer is not mine!");
+  uintptr_t UPtr = reinterpret_cast<uintptr_t>(Ptr);
+  size_t Slot = State.getNearestSlot(UPtr);
+  uintptr_t SlotStart = State.slotToAddr(Slot);
+  AllocationMetadata *Meta = addrToMetadata(UPtr);
+
+  // If this allocation is responsible for crash, never recycle it. Turn the
+  // deallocate() call into a no-op.
+  if (Meta->HasCrashed)
+    return;
+
+  if (Meta->Addr != UPtr) {
+    raiseInternallyDetectedError(UPtr, Error::INVALID_FREE);
+    return;
+  }
+  if (Meta->IsDeallocated) {
+    raiseInternallyDetectedError(UPtr, Error::DOUBLE_FREE);
+    return;
+  }
+
+  // Intentionally scope the mutex here, so that other threads can access the
+  // pool during the expensive markInaccessible() call.
+  {
+    ScopedLock L(PoolMutex);
+
+    // Ensure that the deallocation is recorded before marking the page as
+    // inaccessible. Otherwise, a racy use-after-free will have inconsistent
+    // metadata.
+    Meta->RecordDeallocation();
+
+    // Ensure that the unwinder is not called if the recursive flag is set,
+    // otherwise non-reentrant unwinders may deadlock.
+    if (!getThreadLocals()->RecursiveGuard) {
+      ScopedRecursiveGuard SRG;
+      ScopedLock UL(BacktraceMutex);
+      Meta->DeallocationTrace.RecordBacktrace(Backtrace);
+    }
+  }
+
+  deallocateInGuardedPool(reinterpret_cast<void *>(SlotStart),
+                          State.maximumAllocationSize());
+
+  // And finally, lock again to release the slot back into the pool.
+  ScopedLock L(PoolMutex);
+  freeSlot(Slot);
+}
+
+// Thread-compatible, protected by PoolMutex.
+static bool PreviousRecursiveGuard;
+
+void GuardedPoolAllocator::preCrashReport(void *Ptr) {
+  assert(pointerIsMine(Ptr) && "Pointer is not mine!");
+  uintptr_t InternalCrashAddr = __gwp_asan_get_internal_crash_address(
+      &State, reinterpret_cast<uintptr_t>(Ptr));
+  if (!InternalCrashAddr)
+    disable();
+
+  // If something in the signal handler calls malloc() while dumping the
+  // GWP-ASan report (e.g. backtrace_symbols()), make sure that GWP-ASan doesn't
+  // service that allocation. `PreviousRecursiveGuard` is protected by the
+  // allocator locks taken in disable(), either explicitly above for
+  // externally-raised errors, or implicitly in raiseInternallyDetectedError()
+  // for internally-detected errors.
+  PreviousRecursiveGuard = getThreadLocals()->RecursiveGuard;
+  getThreadLocals()->RecursiveGuard = true;
+}
+
+void GuardedPoolAllocator::postCrashReportRecoverableOnly(void *SignalPtr) {
+  uintptr_t SignalUPtr = reinterpret_cast<uintptr_t>(SignalPtr);
+  uintptr_t InternalCrashAddr =
+      __gwp_asan_get_internal_crash_address(&State, SignalUPtr);
+  uintptr_t ErrorUptr = InternalCrashAddr ?: SignalUPtr;
+
+  AllocationMetadata *Metadata = addrToMetadata(ErrorUptr);
+  Metadata->HasCrashed = true;
+
+  allocateInGuardedPool(
+      reinterpret_cast<void *>(getPageAddr(SignalUPtr, State.PageSize)),
+      State.PageSize);
+
+  // Clear the internal state in order to not confuse the crash handler if a
+  // use-after-free or buffer-overflow comes from a different allocation in the
+  // future.
+  if (InternalCrashAddr) {
+    State.FailureType = Error::UNKNOWN;
+    State.FailureAddress = 0;
+  }
+
+  size_t Slot = State.getNearestSlot(ErrorUptr);
+  // If the slot is available, remove it permanently.
+  for (size_t i = 0; i < FreeSlotsLength; ++i) {
+    if (FreeSlots[i] == Slot) {
+      FreeSlots[i] = FreeSlots[FreeSlotsLength - 1];
+      FreeSlotsLength -= 1;
+      break;
+    }
+  }
+
+  getThreadLocals()->RecursiveGuard = PreviousRecursiveGuard;
+  if (!InternalCrashAddr)
+    enable();
+}
+
+size_t GuardedPoolAllocator::getSize(const void *Ptr) {
+  assert(pointerIsMine(Ptr));
+  ScopedLock L(PoolMutex);
+  AllocationMetadata *Meta = addrToMetadata(reinterpret_cast<uintptr_t>(Ptr));
+  assert(Meta->Addr == reinterpret_cast<uintptr_t>(Ptr));
+  return Meta->RequestedSize;
+}
+
+AllocationMetadata *GuardedPoolAllocator::addrToMetadata(uintptr_t Ptr) const {
+  return &Metadata[State.getNearestSlot(Ptr)];
+}
+
+size_t GuardedPoolAllocator::reserveSlot() {
+  // Avoid potential reuse of a slot before we have made at least a single
+  // allocation in each slot. Helps with our use-after-free detection.
+  if (NumSampledAllocations < State.MaxSimultaneousAllocations)
+    return NumSampledAllocations++;
+
+  if (FreeSlotsLength == 0)
+    return kInvalidSlotID;
+
+  size_t ReservedIndex = getRandomUnsigned32() % FreeSlotsLength;
+  size_t SlotIndex = FreeSlots[ReservedIndex];
+  FreeSlots[ReservedIndex] = FreeSlots[--FreeSlotsLength];
+  return SlotIndex;
+}
+
+void GuardedPoolAllocator::freeSlot(size_t SlotIndex) {
+  assert(FreeSlotsLength < State.MaxSimultaneousAllocations);
+  FreeSlots[FreeSlotsLength++] = SlotIndex;
+}
+
+uint32_t GuardedPoolAllocator::getRandomUnsigned32() {
+  uint32_t RandomState = getThreadLocals()->RandomState;
+  RandomState ^= RandomState << 13;
+  RandomState ^= RandomState >> 17;
+  RandomState ^= RandomState << 5;
+  getThreadLocals()->RandomState = RandomState;
+  return RandomState;
+}
+} // namespace gwp_asan