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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/gwp_asan/client/sampling_partitionalloc_shims.h"
#include <algorithm>
#include <utility>
#include "components/crash/core/common/crash_key.h"
#include "components/gwp_asan/client/export.h"
#include "components/gwp_asan/client/guarded_page_allocator.h"
#include "components/gwp_asan/client/sampling_state.h"
#include "components/gwp_asan/common/crash_key_name.h"
#include "partition_alloc/flags.h"
#include "partition_alloc/partition_alloc.h"
namespace gwp_asan {
namespace internal {
namespace {
SamplingState<PARTITIONALLOC> sampling_state;
// The global allocator singleton used by the shims. Implemented as a global
// pointer instead of a function-local static to avoid initialization checks
// for every access.
GuardedPageAllocator* gpa = nullptr;
bool AllocationHook(void** out,
partition_alloc::AllocFlags flags,
size_t size,
const char* type_name) {
if (sampling_state.Sample(size)) [[unlikely]] {
// Ignore allocation requests with unknown flags.
// TODO(crbug.com/40277643): Add support for memory tagging in GWP-Asan.
constexpr auto kKnownFlags = partition_alloc::AllocFlags::kReturnNull |
partition_alloc::AllocFlags::kZeroFill;
if (!ContainsFlags(kKnownFlags, flags)) {
// Skip if |flags| is not a subset of |kKnownFlags|.
// i.e. if we find an unknown flag.
return false;
}
if (void* allocation = gpa->Allocate(size, 0, type_name)) {
*out = allocation;
return true;
}
}
return false;
}
bool FreeHook(void* address) {
if (gpa->PointerIsMine(address)) [[unlikely]] {
gpa->Deallocate(address);
return true;
}
return false;
}
bool ReallocHook(size_t* out, void* address) {
if (gpa->PointerIsMine(address)) [[unlikely]] {
*out = gpa->GetRequestedSize(address);
return true;
}
return false;
}
} // namespace
// We expose the allocator singleton for unit tests.
GWP_ASAN_EXPORT GuardedPageAllocator& GetPartitionAllocGpaForTesting() {
return *gpa;
}
bool InstallPartitionAllocHooks(
const AllocatorSettings& settings,
GuardedPageAllocator::OutOfMemoryCallback callback) {
static crash_reporter::CrashKeyString<24> pa_crash_key(
kPartitionAllocCrashKey);
gpa = new GuardedPageAllocator();
if (!gpa->Init(settings, std::move(callback), true)) {
return false;
}
pa_crash_key.Set(gpa->GetCrashKey());
sampling_state.Init(settings.sampling_frequency);
sampling_state.SetSampleSizeRestriction(settings.sampling_min_size,
settings.sampling_max_size);
// TODO(vtsyrklevich): Allow SetOverrideHooks to be passed in so we can hook
// PDFium's PartitionAlloc fork.
partition_alloc::PartitionAllocHooks::SetOverrideHooks(
&AllocationHook, &FreeHook, &ReallocHook);
return true;
}
} // namespace internal
} // namespace gwp_asan
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