Skip to content

src: fix pointer alignment #61336

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
jhofstee wants to merge 1 commit into
base: main
Choose a base branch
from
+9 −8
Open

src: fix pointer alignment #61336

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
17 changes: 9 additions & 8 deletions src/node_mem-inl.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@

namespace node {
namespace mem {
static constexpr size_t kReserveSizeAndAlign =
std::max(sizeof(size_t), alignof(max_align_t));

template <typename Class, typename AllocatorStruct>
AllocatorStruct NgLibMemoryManager<Class, AllocatorStruct>::MakeAllocator() {
Expand All @@ -30,19 +32,18 @@ void* NgLibMemoryManager<Class, T>::ReallocImpl(void* ptr,
char* original_ptr = nullptr;

// We prepend each allocated buffer with a size_t containing the full
// size of the allocation.
if (size > 0) size += sizeof(size_t);
// size of the allocation, while keeping the returned pointer aligned.
if (size > 0) size += kReserveSizeAndAlign;

if (ptr != nullptr) {
// We are free()ing or re-allocating.
original_ptr = static_cast<char*>(ptr) - sizeof(size_t);
original_ptr = static_cast<char*>(ptr) - kReserveSizeAndAlign;
previous_size = *reinterpret_cast<size_t*>(original_ptr);
// This means we called StopTracking() on this pointer before.
if (previous_size == 0) {
// Fall back to the standard Realloc() function.
char* ret = UncheckedRealloc(original_ptr, size);
if (ret != nullptr)
ret += sizeof(size_t);
if (ret != nullptr) ret += kReserveSizeAndAlign;
return ret;
}
}
Expand All @@ -62,7 +63,7 @@ void* NgLibMemoryManager<Class, T>::ReallocImpl(void* ptr,
manager->env()->external_memory_accounter()->Update(
manager->env()->isolate(), new_size);
*reinterpret_cast<size_t*>(mem) = size;
mem += sizeof(size_t);
mem += kReserveSizeAndAlign;
} else if (size == 0) {
manager->DecreaseAllocatedSize(previous_size);
manager->env()->external_memory_accounter()->Decrease(
Expand Down Expand Up @@ -95,8 +96,8 @@ void* NgLibMemoryManager<Class, T>::CallocImpl(size_t nmemb,

template <typename Class, typename T>
void NgLibMemoryManager<Class, T>::StopTrackingMemory(void* ptr) {
size_t* original_ptr = reinterpret_cast<size_t*>(
static_cast<char*>(ptr) - sizeof(size_t));
size_t* original_ptr =
reinterpret_cast<size_t*>(static_cast<char*>(ptr) - kReserveSizeAndAlign);
Class* manager = static_cast<Class*>(this);
manager->DecreaseAllocatedSize(*original_ptr);
manager->env()->external_memory_accounter()->Decrease(
Expand Down
Loading