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guard negative operands in MathLib::value shift operators #8639

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guard negative operands in MathLib::value shift operators #8639

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4 changes: 2 additions & 2 deletions lib/mathlib.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -266,7 +266,7 @@ MathLib::value MathLib::value::shiftLeft(const MathLib::value &v) const
if (!isInt() || !v.isInt())
throw InternalError(nullptr, "Shift operand is not integer");
MathLib::value ret(*this);
if (v.mIntValue >= MathLib::bigint_bits) {
if (v.mIntValue < 0 || v.mIntValue >= MathLib::bigint_bits || ret.mIntValue < 0) {
return ret;
}
ret.mIntValue <<= v.mIntValue;
Expand All @@ -278,7 +278,7 @@ MathLib::value MathLib::value::shiftRight(const MathLib::value &v) const
if (!isInt() || !v.isInt())
throw InternalError(nullptr, "Shift operand is not integer");
MathLib::value ret(*this);
if (v.mIntValue >= MathLib::bigint_bits) {
if (v.mIntValue < 0 || v.mIntValue >= MathLib::bigint_bits) {
return ret;
}
ret.mIntValue >>= v.mIntValue;
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15 changes: 15 additions & 0 deletions test/testmathlib.cpp
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Expand Up @@ -64,6 +64,7 @@ class TestMathLib : public TestFixture {
TEST_CASE(tan);
TEST_CASE(abs);
TEST_CASE(toString);
TEST_CASE(valueShift);
}

void isGreater() const {
Expand Down Expand Up @@ -1511,6 +1512,20 @@ class TestMathLib : public TestFixture {
ASSERT_EQUALS("2.22507385851e-308", MathLib::toString(std::numeric_limits<double>::min()));
ASSERT_EQUALS("1.79769313486e+308", MathLib::toString(std::numeric_limits<double>::max()));
}

void valueShift() const {
// ordinary shifts
ASSERT_EQUALS("16", (MathLib::value("1") << MathLib::value("4")).str());
ASSERT_EQUALS("64", (MathLib::value("256") >> MathLib::value("2")).str());

// a large hex literal is not negative as a string but parses to a negative
// bigint; shifting it must not be performed (left shift of a negative value
// and shifting by a negative count are both undefined). the operand is
// returned unchanged, as already done for counts >= bigint_bits.
ASSERT_EQUALS("9223372036854775808U", (MathLib::value("0x8000000000000000") << MathLib::value("1")).str());
ASSERT_EQUALS("1", (MathLib::value("1") << MathLib::value("0x8000000000000000")).str());
ASSERT_EQUALS("1", (MathLib::value("1") >> MathLib::value("0x8000000000000000")).str());
}
};

REGISTER_TEST(TestMathLib)
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