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Fix #14948 FP bufferAccessOutOfBounds after container size check #8763

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Fix #14948 FP bufferAccessOutOfBounds after container size check #8763

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0b19a52
Update checkbufferoverrun.cpp
chrchr-github Jul 29, 2026
88a9426
Update testbufferoverrun.cpp
chrchr-github Jul 29, 2026
31b88ba
Update checkbufferoverrun.cpp
chrchr-github Jul 29, 2026
13bc2fa
Allow possible values
web-flow Aug 4, 2026
d9b785a
Format
web-flow Aug 4, 2026
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11 changes: 9 additions & 2 deletions lib/checkbufferoverrun.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,9 @@ static const ValueFlow::Value *getBufferSizeValue(const Token *tok)
auto it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), std::mem_fn(&ValueFlow::Value::isBufferSizeValue));
if (it != tokenValues.cend())
return &*it;
it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), std::mem_fn(&ValueFlow::Value::isContainerSizeValue));
it = std::find_if(tokenValues.cbegin(), tokenValues.cend(), [](const ValueFlow::Value& v) {
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return v.isContainerSizeValue() && !v.isImpossible();
});
return it == tokenValues.cend() ? nullptr : &*it;
}

Expand Down Expand Up @@ -588,6 +590,8 @@ ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok, cons
ValueFlow::Value bufSizeVal;
bufSizeVal.valueType = ValueFlow::Value::ValueType::BUFFER_SIZE;
bufSizeVal.intvalue = value->intvalue * elementSize;
bufSizeVal.valueKind = value->valueKind;
bufSizeVal.errorPath = value->errorPath;
return bufSizeVal;
}
}
Expand Down Expand Up @@ -721,7 +725,10 @@ void CheckBufferOverrunImpl::bufferOverflow()

void CheckBufferOverrunImpl::bufferOverflowError(const Token *tok, const ValueFlow::Value *value, Certainty certainty)
{
reportError(getErrorPath(tok, value, "Buffer overrun"), Severity::error, "bufferAccessOutOfBounds", "Buffer is accessed out of bounds: " + (tok ? getRealBufferTok(tok)->expressionString() : "buf"), CWE_BUFFER_OVERRUN, certainty);
const auto errorPath = getErrorPath(tok, value, "Buffer overrun");
const auto severity = !value || value->isKnown() ? Severity::error : Severity::warning;
const std::string msg = "Buffer is accessed out of bounds: " + (tok ? getRealBufferTok(tok)->expressionString() : "buf");
reportError(errorPath, severity, "bufferAccessOutOfBounds", msg, CWE_BUFFER_OVERRUN, certainty);
}

//---------------------------------------------------------------------------
Expand Down
15 changes: 15 additions & 0 deletions test/testbufferoverrun.cpp
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Expand Up @@ -3564,6 +3564,21 @@ class TestBufferOverrun : public TestFixture {
" memset(&a[i], 0, sizeof(a));\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4:16]: (error) Buffer is accessed out of bounds: &a[i] [bufferAccessOutOfBounds]\n", errout_str());

check("void f(const std::vector<uint8_t>& s) {\n" // #14948
" if (s.size() < 4)\n"
" return;\n"
" uint32_t u = 0;\n"
" std::memcpy(&u, &s[0], sizeof(u));\n"
"}\n");
ASSERT_EQUALS("", errout_str());

check("void f(const std::vector<uint8_t>& s) {\n"
" if (s.size() == 2) {}\n"
" uint32_t u = 0;\n"
" std::memcpy(&u, &s[0], sizeof(u));\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4:21]: (warning) Buffer is accessed out of bounds: &s[0] [bufferAccessOutOfBounds]\n", errout_str());
}

void buffer_overrun_errorpath() {
Expand Down
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