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ICU-23335 Fix undefined behavior and null-deref in date_format_fuzzer #3888

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ICU-23335 Fix undefined behavior and null-deref in date_format_fuzzer #3888

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42 changes: 25 additions & 17 deletions icu4c/source/test/fuzzer/date_format_fuzzer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,10 +31,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
};
int32_t numStyles = sizeof(styles) / sizeof(icu::DateFormat::EStyle);

icu::DateFormat::EStyle dateStyle;
icu::DateFormat::EStyle timeStyle;
if (size < sizeof(rnd) + sizeof(date) + 2*sizeof(rnd2) +
sizeof(dateStyle) + sizeof(timeStyle) ) {
if (size < sizeof(rnd) + sizeof(date) + 4*sizeof(uint8_t)) {
return 0;
}
icu::StringPiece fuzzData(reinterpret_cast<const char *>(data), size);
Expand All @@ -43,10 +40,15 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
fuzzData.remove_prefix(sizeof(rnd));
icu::Locale locale = GetRandomLocale(rnd);

std::memcpy(&dateStyle, fuzzData.data(), sizeof(dateStyle));
fuzzData.remove_prefix(sizeof(dateStyle));
std::memcpy(&timeStyle, fuzzData.data(), sizeof(timeStyle));
fuzzData.remove_prefix(sizeof(timeStyle));
// Use styles[] lookup with modulo for all style variables to avoid
// undefined behavior from loading invalid enum values.
std::memcpy(&rnd2, fuzzData.data(), sizeof(rnd2));
icu::DateFormat::EStyle dateStyle = styles[rnd2 % numStyles];
fuzzData.remove_prefix(sizeof(rnd2));

std::memcpy(&rnd2, fuzzData.data(), sizeof(rnd2));
icu::DateFormat::EStyle timeStyle = styles[rnd2 % numStyles];
fuzzData.remove_prefix(sizeof(rnd2));

std::memcpy(&rnd2, fuzzData.data(), sizeof(rnd2));
icu::DateFormat::EStyle dateStyle2 = styles[rnd2 % numStyles];
Expand All @@ -61,26 +63,31 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {

std::unique_ptr<icu::DateFormat> df(
icu::DateFormat::createDateTimeInstance(dateStyle, timeStyle, locale));
icu::UnicodeString appendTo;
df->format(date, appendTo);
if (df) {
icu::UnicodeString appendTo;
df->format(date, appendTo);
}

df.reset(
icu::DateFormat::createDateTimeInstance(dateStyle2, timeStyle2, locale));
appendTo.remove();
df->format(date, appendTo);
if (df) {
icu::UnicodeString appendTo;
df->format(date, appendTo);
}

icu::UnicodeString skeleton = icu::UnicodeString::fromUTF8(fuzzData);

UErrorCode status = U_ZERO_ERROR;
appendTo.remove();
df.reset(icu::DateFormat::createInstanceForSkeleton(skeleton, status));
if (U_SUCCESS(status)) {
if (U_SUCCESS(status) && df) {
icu::UnicodeString appendTo;
df->format(date, appendTo);
}

status = U_ZERO_ERROR;
appendTo.remove();
df.reset(icu::DateFormat::createInstanceForSkeleton(skeleton, locale, status));
if (U_SUCCESS(status)) {
if (U_SUCCESS(status) && df) {
icu::UnicodeString appendTo;
df->format(date, appendTo);
}

Expand All @@ -91,10 +98,11 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
df.reset(
icu::DateFormat::createDateTimeInstance(dateStyle2, timeStyle2, locale2));

status = U_ZERO_ERROR;
UDateFormat* udf = udat_open(UDAT_PATTERN, UDAT_PATTERN, str.c_str(), nullptr, 0,
skeleton.getBuffer(), skeleton.length(), &status);
if (udf && U_SUCCESS(status)) {
udat_close(udf);
}
return EXIT_SUCCESS;
return 0;
}