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Fix 11194: FN: knownConditionTrueFalse (#4452) 

* Fix 11194: FN: knownConditionTrueFalse

* Format
This commit is contained in:
Paul Fultz II 2022-09-08 11:51:44 -05:00 committed by GitHub
parent 92845295b8
commit f83b8dd385
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2 changed files with 132 additions and 64 deletions
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112
lib/valueflow.cpp
View File

@ -5088,13 +5088,58 @@ static void valueFlowSymbolic(TokenList* tokenlist, SymbolDatabase* symboldataba
}
}
static void valueFlowSymbolicIdentity(TokenList* tokenlist)
static const Token* isStrlenOf(const Token* tok, const Token* expr, int depth = 10)
{
for (Token* tok = tokenlist->front(); tok; tok = tok->next()) {
if (depth < 0)
return nullptr;
if (!tok)
return nullptr;
if (!expr)
return nullptr;
if (expr->exprId() == 0)
return nullptr;
if (Token::simpleMatch(tok->previous(), "strlen (")) {
if (tok->astOperand2()->exprId() == expr->exprId())
return tok;
} else {
for (const ValueFlow::Value& v : tok->values()) {
if (!v.isSymbolicValue())
continue;
if (!v.isKnown())
continue;
if (v.intvalue != 0)
continue;
if (const Token* next = isStrlenOf(v.tokvalue, expr, depth - 1))
return next;
}
}
return nullptr;
}
static void valueFlowSymbolicOperators(TokenList* tokenlist, SymbolDatabase* symboldatabase)
{
for (const Scope* scope : symboldatabase->functionScopes) {
for (Token* tok = const_cast<Token*>(scope->bodyStart); tok != scope->bodyEnd; tok = tok->next()) {
if (tok->hasKnownIntValue())
continue;
if (!Token::Match(tok, "*|/|<<|>>|^|+|-|%or%"))
if (Token::Match(tok, "abs|labs|llabs|fabs|fabsf|fabsl (")) {
const Token* arg = tok->next()->astOperand2();
if (!arg)
continue;
ValueFlow::Value c = inferCondition(">=", arg, 0);
if (!c.isKnown())
continue;
ValueFlow::Value v = makeSymbolic(arg);
v.errorPath = c.errorPath;
v.errorPath.emplace_back(tok, "Passed to " + tok->str());
if (c.intvalue == 0)
v.setImpossible();
else
v.setKnown();
setTokenValue(tok->next(), v, tokenlist->getSettings());
} else if (Token::Match(tok, "*|/|<<|>>|^|+|-|%or%")) {
if (!tok->astOperand1())
continue;
if (!tok->astOperand2())
@ -5125,8 +5170,10 @@ static void valueFlowSymbolicIdentity(TokenList* tokenlist)
continue;
std::vector<ValueFlow::Value> values = {makeSymbolic(vartok)};
std::unordered_set<nonneg int> ids = {vartok->exprId()};
std::copy_if(
vartok->values().begin(), vartok->values().end(), std::back_inserter(values), [&](const ValueFlow::Value& v) {
std::copy_if(vartok->values().begin(),
vartok->values().end(),
std::back_inserter(values),
[&](const ValueFlow::Value& v) {
if (!v.isSymbolicValue())
return false;
if (!v.tokvalue)
@ -5135,33 +5182,33 @@ static void valueFlowSymbolicIdentity(TokenList* tokenlist)
});
for (const ValueFlow::Value& v : values)
setTokenValue(tok, v, tokenlist->getSettings());
} else if (Token::simpleMatch(tok, "[")) {
const Token* arrayTok = tok->astOperand1();
const Token* indexTok = tok->astOperand2();
if (!arrayTok)
continue;
if (!indexTok)
continue;
for (const ValueFlow::Value& value : indexTok->values()) {
if (!value.isSymbolicValue())
continue;
if (value.intvalue != 0)
continue;
if (value.bound == ValueFlow::Value::Bound::Upper)
continue;
if (value.isImpossible() && value.bound != ValueFlow::Value::Bound::Lower)
continue;
if (value.isKnown() && value.bound != ValueFlow::Value::Bound::Point)
continue;
const Token* strlenTok = isStrlenOf(value.tokvalue, arrayTok);
if (!strlenTok)
continue;
ValueFlow::Value v = value;
v.valueType = ValueFlow::Value::ValueType::INT;
v.errorPath.emplace_back(strlenTok, "Return index of string to the first element that is 0");
setTokenValue(tok, v, tokenlist->getSettings());
}
}
}
static void valueFlowSymbolicAbs(TokenList* tokenlist, SymbolDatabase* symboldatabase)
{
for (const Scope* scope : symboldatabase->functionScopes) {
for (Token* tok = const_cast<Token*>(scope->bodyStart); tok != scope->bodyEnd; tok = tok->next()) {
if (!Token::Match(tok, "abs|labs|llabs|fabs|fabsf|fabsl ("))
continue;
if (tok->hasKnownIntValue())
continue;
const Token* arg = tok->next()->astOperand2();
if (!arg)
continue;
ValueFlow::Value c = inferCondition(">=", arg, 0);
if (!c.isKnown())
continue;
ValueFlow::Value v = makeSymbolic(arg);
v.errorPath = c.errorPath;
v.errorPath.emplace_back(tok, "Passed to " + tok->str());
if (c.intvalue == 0)
v.setImpossible();
else
v.setKnown();
setTokenValue(tok->next(), v, tokenlist->getSettings());
}
}
}
@ -8764,8 +8811,7 @@ void ValueFlow::setValues(TokenList *tokenlist, SymbolDatabase* symboldatabase,
while (n > 0 && values < getTotalValues(tokenlist)) {
values = getTotalValues(tokenlist);
valueFlowImpossibleValues(tokenlist, settings);
valueFlowSymbolicIdentity(tokenlist);
valueFlowSymbolicAbs(tokenlist, symboldatabase);
valueFlowSymbolicOperators(tokenlist, symboldatabase);
valueFlowCondition(SymbolicConditionHandler{}, tokenlist, symboldatabase, errorLogger, settings);
valueFlowSymbolicInfer(tokenlist, symboldatabase);
valueFlowArrayBool(tokenlist);

22
test/testvalueflow.cpp
View File

@ -158,6 +158,7 @@ private:
TEST_CASE(valueFlowNotNull);
TEST_CASE(valueFlowSymbolic);
TEST_CASE(valueFlowSymbolicIdentity);
TEST_CASE(valueFlowSymbolicStrlen);
TEST_CASE(valueFlowSmartPointer);
}
@ -7522,6 +7523,27 @@ private:
ASSERT_EQUALS(false, testValueOfXKnown(code, 3U, "a", 0));
}
void valueFlowSymbolicStrlen()
{
const char* code;
code = "int f(char *s) {\n"
" size_t len = strlen(s);\n"
" int x = s[len];\n"
" return x;\n"
"}\n";
ASSERT_EQUALS(true, testValueOfXKnown(code, 4U, 0));
code = "int f(char *s, size_t i) {\n"
" if (i < strlen(s)) {\n"
" int x = s[i];\n"
" return x;\n"
" }\n"
" return 0;\n"
"}\n";
ASSERT_EQUALS(true, testValueOfXImpossible(code, 4U, 0));
}
void valueFlowSmartPointer()
{
const char* code;