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Fix 11461: arrayIndexOutOfBounds false positive #4686

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Merged
danmar merged 2 commits into from
Jan 7, 2023
Merged

Fix 11461: arrayIndexOutOfBounds false positive #4686

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Fix 11461: arrayIndexOutOfBounds false positive
pfultz2 Jan 5, 2023
e26a839
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pfultz2 Jan 5, 2023
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3 changes: 3 additions & 0 deletions lib/valueflow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9197,6 +9197,9 @@ static std::vector<ValueFlow::Value> isOutOfBoundsImpl(const ValueFlow::Value& s
return {};
if (size.bound == ValueFlow::Value::Bound::Lower)
return {};
// Checking for underflow doesnt mean it could be out of bounds
if (indexValue->intvalue == 0)
return {};
ValueFlow::Value value = inferCondition(">=", indexTok, indexValue->intvalue);
if (!value.isKnown())
return {};
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14 changes: 14 additions & 0 deletions test/testbufferoverrun.cpp
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Expand Up @@ -195,6 +195,7 @@ class TestBufferOverrun : public TestFixture {
TEST_CASE(array_index_68); // #6655
TEST_CASE(array_index_69); // #6370
TEST_CASE(array_index_70); // #11355
TEST_CASE(array_index_71); // #11461
TEST_CASE(array_index_multidim);
TEST_CASE(array_index_switch_in_for);
TEST_CASE(array_index_for_in_for); // FP: #2634
Expand Down Expand Up @@ -1912,6 +1913,19 @@ class TestBufferOverrun : public TestFixture {
ASSERT_EQUALS("[test.cpp:3]: (error) Array 'a[5]' accessed at index 5, which is out of bounds.\n", errout.str());
}

// #11461
void array_index_71()
{
check("unsigned int f(unsigned int Idx) {\n"
" if (Idx < 64)\n"
" return 0;\n"
" Idx -= 64;\n"
" int arr[64] = { 0 };\n"
" return arr[Idx];\n"
"}\n");
ASSERT_EQUALS("", errout.str());
}

void array_index_multidim() {
check("void f()\n"
"{\n"
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