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Add guards around nativeProps usage to prevent race conditions #52646

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Add guards around nativeProps usage to prevent race conditions #52646

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1 change: 1 addition & 0 deletions packages/react-native/ReactCommon/react/renderer/core/ShadowNode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -139,6 +139,7 @@ ShadowNode::ShadowNode(
std::shared_ptr<ShadowNode> ShadowNode::clone(
const ShadowNodeFragment& fragment) const {
const auto& family = *family_;
std::lock_guard<std::recursive_mutex> npGuard(family.nativePropsMutex);
const auto& componentDescriptor = family.componentDescriptor_;
if (family.nativeProps_DEPRECATED != nullptr) {
auto propsParserContext = PropsParserContext{family_->getSurfaceId(), {}};
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2 changes: 2 additions & 0 deletions packages/react-native/ReactCommon/react/renderer/core/ShadowNodeFamily.h
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Expand Up @@ -9,6 +9,7 @@

#include <memory>
#include <shared_mutex>
#include <mutex>

#include <react/renderer/core/EventEmitter.h>
#include <react/renderer/core/InstanceHandle.h>
Expand Down Expand Up @@ -118,6 +119,7 @@ class ShadowNodeFamily final : public jsi::NativeState {
* architecture and will be removed in the future.
*/
mutable std::unique_ptr<folly::dynamic> nativeProps_DEPRECATED;
mutable std::recursive_mutex nativePropsMutex;

@javache javache Nov 21, 2025

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Any reason this needs to be a recursive mutex instead of a plain one?

Does this need to be ShadowNodeFamily scoped, or would a single global mutex on UIManager be sufficient?

@OrfeasZ OrfeasZ Nov 21, 2025

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I don't know enough about the internals of react native, so took the safe approach of using a recursive one to prevent deadlocks in the case the critical path ends up trying to acquire the lock again recursively. That said, if that can't happen, it could be replaced with a regular mutex.

As for scoping, I'm not sure (again due to lack of internals knowledge). The main issue this tries to address is concurrent writes / reads to the nativeProps_DEPRECATED field, which is why I added it there, trying to keep the locking exactly to where it's needed.

@javache javache Jun 26, 2026

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Let's stick with a normal mutex here - I don't see any way this could be re-entrant.


/**
* @return tag for the ShadowNodeFamily.
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3 changes: 3 additions & 0 deletions packages/react-native/ReactCommon/react/renderer/uimanager/UIManager.cpp
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Expand Up @@ -118,6 +118,7 @@ std::shared_ptr<ShadowNode> UIManager::cloneNode(
auto props = ShadowNodeFragment::propsPlaceholder();

if (!rawProps.isEmpty()) {
std::lock_guard<std::recursive_mutex> npGuard(family.nativePropsMutex);
if (family.nativeProps_DEPRECATED != nullptr) {
// 1. update the nativeProps_DEPRECATED props.
//
Expand Down Expand Up @@ -426,6 +427,7 @@ void UIManager::setNativeProps_DEPRECATED(
const std::shared_ptr<const ShadowNode>& shadowNode,
RawProps rawProps) const {
auto& family = shadowNode->getFamily();
family.nativePropsMutex.lock();
if (family.nativeProps_DEPRECATED) {
// Values in `rawProps` patch (take precedence over)
// `nativeProps_DEPRECATED`. For example, if both `nativeProps_DEPRECATED`
Expand All @@ -440,6 +442,7 @@ void UIManager::setNativeProps_DEPRECATED(
family.nativeProps_DEPRECATED =
std::make_unique<folly::dynamic>((folly::dynamic)rawProps);
}
family.nativePropsMutex.unlock();

shadowTreeRegistry_.visit(
family.getSurfaceId(), [&](const ShadowTree& shadowTree) {
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