[gwp-asan] Implement malloc_iterate.

[eugenis]

Summary

This is an Android-specific interface for iterating over all live
allocations in a memory range.

[hctim]

compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp

183

Nit: Cb

compiler-rt/lib/gwp_asan/guarded_pool_allocator.h

107

// Execute the callback `Cb()` for every allocation that lies between [Base, Base + Size)

110

Nit: Cb

[merge_guards_bot]

Unit tests: unknown.

clang-tidy: unknown.

clang-format: unknown.

Build artifacts: diff.json, console-log.txt

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[eugenis]

address comments

[merge_guards_bot]

Unit tests: unknown.

clang-tidy: unknown.

clang-format: unknown.

Build artifacts: diff.json, console-log.txt

Pre-merge checks is in beta. Report issue. Please join beta or enable it for your project.

compiler-rt/lib/gwp_asan/guarded_pool_allocator.h

public:
   // pool using the provided options. See options.inc for runtime configuration
   // options.
   void init(const options::Options &Opts);
   void uninitTestOnly();
 
   void disable();
   void enable();
 
+  typedef void (*iterate_callback)(uintptr_t base, size_t size, void *arg);
+  // Execute the callback Cb for every allocation the lies in [Base, Base + Size).
+  // Must be called while the allocator is disabled. The callback can not
+  // allocate.
+  void iterate(void *Base, size_t Size, iterate_callback Cb, void *Arg);
+
   // Return whether the allocation should be randomly chosen for sampling.
   GWP_ASAN_ALWAYS_INLINE bool shouldSample() {
     // NextSampleCounter == 0 means we "should regenerate the counter".
     //                   == 1 means we "should sample this allocation".
     // AdjustedSampleRatePlusOne is designed to intentionally underflow. This
     // class must be valid when zero-initialised, and we wish to sample as
     // infrequently as possible when this is the case, hence we underflow to
     // UINT32_MAX.

compiler-rt/lib/gwp_asan/guarded_pool_allocator.cpp

void GuardedPoolAllocator::init(const options::Options &Opts) {
   if (Opts.InstallForkHandlers)
     installAtFork();
 }
 
 void GuardedPoolAllocator::disable() { PoolMutex.lock(); }
 
 void GuardedPoolAllocator::enable() { PoolMutex.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 < MaxSimultaneousAllocations; ++i) {
+    const AllocationMetadata &Meta = Metadata[i];
+    if (Meta.Addr && !Meta.IsDeallocated && Meta.Addr >= Start &&
+        Meta.Addr < Start + Size)
+      Cb(Meta.Addr, Meta.Size, Arg);
+  }
+}
+
 void GuardedPoolAllocator::uninitTestOnly() {
   if (GuardedPagePool) {
     unmapMemory(reinterpret_cast<void *>(GuardedPagePool),
                 GuardedPagePoolEnd - GuardedPagePool);
     GuardedPagePool = 0;
     GuardedPagePoolEnd = 0;
   }
   if (Metadata) {

compiler-rt/lib/gwp_asan/tests/CMakeLists.txt

 include(CompilerRTCompile)
 
 set(GWP_ASAN_UNITTEST_CFLAGS
   ${COMPILER_RT_UNITTEST_CFLAGS}
   ${COMPILER_RT_GTEST_CFLAGS}
   -I${COMPILER_RT_SOURCE_DIR}/lib/
   -O2
   -g)
 
 file(GLOB GWP_ASAN_HEADERS ../*.h)
 set(GWP_ASAN_UNITTESTS
   optional/printf_sanitizer_common.cpp
   alignment.cpp
   backtrace.cpp
   basic.cpp
   compression.cpp
+  iterate.cpp
   driver.cpp
   mutex_test.cpp
   slot_reuse.cpp
   thread_contention.cpp
   harness.cpp
   enable_disable.cpp)
 
 set(GWP_ASAN_UNIT_TEST_HEADERS

compiler-rt/lib/gwp_asan/tests/iterate.cpp

+//===-- iterate.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/tests/harness.h"
+
+TEST_F(CustomGuardedPoolAllocator, Iterate) {
+  InitNumSlots(7);
+  std::vector<std::pair<void *, size_t>> Allocated;
+  auto alloc = [&](size_t size) {
+    Allocated.push_back({GPA.allocate(size), size});
+  };
+
+  void *Ptr = GPA.allocate(5);
+  alloc(2);
+  alloc(1);
+  alloc(100);
+  GPA.deallocate(Ptr);
+  alloc(42);
+  std::sort(Allocated.begin(), Allocated.end());
+
+  GPA.disable();
+  void *Base = Allocated[0].first;
+  size_t Size = reinterpret_cast<size_t>(Allocated.back().first) -
+                reinterpret_cast<size_t>(Base) + 1;
+  std::vector<std::pair<void *, size_t>> Found;
+  GPA.iterate(
+      Base, Size,
+      [](uintptr_t Addr, size_t Size, void *Arg) {
+        reinterpret_cast<std::vector<std::pair<void *, size_t>> *>(Arg)
+            ->push_back({(void *)Addr, Size});
+      },
+      reinterpret_cast<void *>(&Found));
+  GPA.enable();
+
+  std::sort(Found.begin(), Found.end());
+  EXPECT_EQ(Allocated, Found);
+
+  // Now without the last allocation.
+  GPA.disable();
+  Size = reinterpret_cast<size_t>(Allocated.back().first) -
+         reinterpret_cast<size_t>(Base); // Allocated.back() is out of range.
+  Found.clear();
+  GPA.iterate(
+      Base, Size,
+      [](uintptr_t Addr, size_t Size, void *Arg) {
+        reinterpret_cast<std::vector<std::pair<void *, size_t>> *>(Arg)
+            ->push_back({(void *)Addr, Size});
+      },
+      reinterpret_cast<void *>(&Found));
+  GPA.enable();
+
+  // We should have found every allocation but the last.
+  // Remove it and compare the rest.
+  std::sort(Found.begin(), Found.end());
+  GPA.deallocate(Allocated.back().first);
+  Allocated.pop_back();
+  EXPECT_EQ(Allocated, Found);
+
+  for (auto PS : Allocated)
+    GPA.deallocate(PS.first);
+}

compiler-rt/lib/scudo/standalone/combined.h

auto Lambda = [this, From, To, Callback, Arg](uptr Block) {
         if (useMemoryTagging())
           TaggedChunk = loadTag(Chunk);
         Callback(TaggedChunk, getSize(reinterpret_cast<void *>(Chunk), &Header),
                  Arg);
       }
     };
     Primary.iterateOverBlocks(Lambda);
     Secondary.iterateOverBlocks(Lambda);
+#ifdef GWP_ASAN_HOOKS
+    GuardedAlloc.iterate(reinterpret_cast<void *>(Base), Size, Callback, Arg);
+#endif
   }
 
   bool canReturnNull() {
     initThreadMaybe();
     return Options.MayReturnNull;
   }
 
   // TODO(kostyak): implement this as a "backend" to mallopt.