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Fix crash in RawPropsKeyMap::at() for out-of-bounds prop name lengths #55534

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Fix crash in RawPropsKeyMap::at() for out-of-bounds prop name lengths #55534

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28 changes: 11 additions & 17 deletions packages/react-native/ReactCommon/react/renderer/core/RawPropsKey.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,6 @@
#include <cassert>
#include <cstring>

#include <react/debug/react_native_assert.h>
#include <react/renderer/core/RawPropsPrimitives.h>

namespace facebook::react {
Expand All @@ -20,34 +19,29 @@ void RawPropsKey::render(char* buffer, RawPropsPropNameLength* length)
const noexcept {
*length = 0;

// Prefix
constexpr size_t maxLength = kPropNameLengthHardCap - 1;

auto appendSegment = [&](const char* segment) {
auto copyLen = std::min(std::strlen(segment), maxLength - *length);
std::memcpy(buffer + *length, segment, copyLen);
*length += static_cast<RawPropsPropNameLength>(copyLen);
};

if (prefix != nullptr) {
auto prefixLength =
static_cast<RawPropsPropNameLength>(std::strlen(prefix));
std::memcpy(buffer, prefix, prefixLength);
*length = prefixLength;
appendSegment(prefix);
}

// Name
auto nameLength = static_cast<RawPropsPropNameLength>(std::strlen(name));
std::memcpy(buffer + *length, name, nameLength);
*length += nameLength;
appendSegment(name);

// Suffix
if (suffix != nullptr) {
auto suffixLength =
static_cast<RawPropsPropNameLength>(std::strlen(suffix));
std::memcpy(buffer + *length, suffix, suffixLength);
*length += suffixLength;
appendSegment(suffix);
}
react_native_assert(*length < kPropNameLengthHardCap);
}

RawPropsKey::operator std::string() const noexcept {
auto buffer = std::array<char, kPropNameLengthHardCap>();
RawPropsPropNameLength length = 0;
render(buffer.data(), &length);
react_native_assert(length < kPropNameLengthHardCap);
return std::string{buffer.data(), length};
}

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5 changes: 4 additions & 1 deletion packages/react-native/ReactCommon/react/renderer/core/RawPropsKeyMap.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ void RawPropsKeyMap::reindex() noexcept {

buckets_.resize(kPropNameLengthHardCap);

auto length = RawPropsPropNameLength{0};
RawPropsPropNameLength length = 0;
for (size_t i = 0; i < items_.size(); i++) {
auto& item = items_[i];
if (item.length != length) {
Expand All @@ -96,6 +96,9 @@ RawPropsValueIndex RawPropsKeyMap::at(
RawPropsPropNameLength length) noexcept {
react_native_assert(length > 0);
react_native_assert(length < kPropNameLengthHardCap);
if (length == 0 || length >= kPropNameLengthHardCap) [[unlikely]] {
return kRawPropsValueIndexEmpty;
}
// 1. Find the bucket.
auto lower = int{buckets_[length - 1]};
auto upper = int{buckets_[length]} - 1;
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