Skip to content

GH-50057: [C++] Avoid signed overflow in Decimal FromString exponent #50058

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
metsw24-max wants to merge 1 commit into
base: main
Choose a base branch
from
+19 −7
Open

GH-50057: [C++] Avoid signed overflow in Decimal FromString exponent #50058

Show file tree
Hide file tree
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
24 changes: 18 additions & 6 deletions cpp/src/arrow/util/decimal.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -881,9 +881,15 @@ Status DecimalFromString(const char* type_name, std::string_view s, Decimal* out

int32_t parsed_scale = 0;
if (dec.has_exponent) {
auto adjusted_exponent = dec.exponent;
parsed_scale =
-adjusted_exponent + static_cast<int32_t>(dec.fractional_digits.size());
// parsed_scale = -exponent + fractional_digits, computed with overflow
// detection: an exponent of INT32_MIN ("0E-2147483648") makes the negation,
// and a near-INT32_MIN exponent the addition, signed-overflow UB otherwise.
if (internal::SubtractWithOverflow(
static_cast<int32_t>(dec.fractional_digits.size()), dec.exponent,
&parsed_scale)) {
return Status::Invalid("The string '", s, "' cannot be represented as ",
type_name);
}
} else {
parsed_scale = static_cast<int32_t>(dec.fractional_digits.size());
}
Expand Down Expand Up @@ -945,9 +951,15 @@ Status SimpleDecimalFromString(const char* type_name, std::string_view s,

int32_t parsed_scale = 0;
if (dec.has_exponent) {
auto adjusted_exponent = dec.exponent;
parsed_scale =
-adjusted_exponent + static_cast<int32_t>(dec.fractional_digits.size());
// parsed_scale = -exponent + fractional_digits, computed with overflow
// detection: an exponent of INT32_MIN ("0E-2147483648") makes the negation,
// and a near-INT32_MIN exponent the addition, signed-overflow UB otherwise.
if (internal::SubtractWithOverflow(
static_cast<int32_t>(dec.fractional_digits.size()), dec.exponent,
&parsed_scale)) {
return Status::Invalid("The string '", s, "' cannot be represented as ",
type_name);
}
} else {
parsed_scale = static_cast<int32_t>(dec.fractional_digits.size());
}
Expand Down
2 changes: 1 addition & 1 deletion cpp/src/arrow/util/decimal_test.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -136,7 +136,7 @@ class DecimalFromStringTest : public ::testing::Test {
for (const std::string invalid_value :
{"-", "0.0.0", "0-13-32", "a", "-23092.235-", "-+23092.235", "+-23092.235",
"00a", "1e1a", "0.00123D/3", "1.23eA8", "1.23E+3A", "-1.23E--5",
"1.2345E+++07"}) {
"1.2345E+++07", "0E-2147483648", "1.0E-2147483647"}) {
ARROW_SCOPED_TRACE("invalid_value = '", invalid_value, "'");
ASSERT_RAISES(Invalid, DecimalType::FromString(invalid_value));
}
Expand Down
Loading