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Fix 9755: false negative: access of moved variable in conditional code (#4459) 

* Fix 9755: false negative: access of moved variable in conditional code

* Format
This commit is contained in:
Paul Fultz II 2022-09-11 05:32:01 -05:00 committed by GitHub
parent 76d1b9f31a
commit 43caa32abf
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6 changed files with 78 additions and 66 deletions
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54
lib/astutils.cpp
View File

@ -2897,6 +2897,60 @@ bool isConstVarExpression(const Token *tok, std::function<bool(const Token*)> sk
return false;
}
static ExprUsage getFunctionUsage(const Token* tok, int indirect, const Settings* settings)
{
const bool addressOf = tok->astParent() && tok->astParent()->isUnaryOp("&");
int argnr;
const Token* ftok = getTokenArgumentFunction(tok, argnr);
if (!ftok)
return ExprUsage::None;
if (ftok->function()) {
std::vector<const Variable*> args = getArgumentVars(ftok, argnr);
for (const Variable* arg : args) {
if (!arg)
continue;
if (arg->isReference())
return ExprUsage::PassedByReference;
}
if (!args.empty() && indirect == 0 && !addressOf)
return ExprUsage::Used;
} else {
const bool isnullbad = settings->library.isnullargbad(ftok, argnr + 1);
if (indirect == 0 && astIsPointer(tok) && !addressOf && isnullbad)
return ExprUsage::Used;
bool hasIndirect = false;
const bool isuninitbad = settings->library.isuninitargbad(ftok, argnr + 1, indirect, &hasIndirect);
if (isuninitbad && (!addressOf || isnullbad))
return ExprUsage::Used;
}
return ExprUsage::Inconclusive;
}
ExprUsage getExprUsage(const Token* tok, int indirect, const Settings* settings)
{
if (indirect > 0 && tok->astParent()) {
if (Token::Match(tok->astParent(), "%assign%") && astIsRHS(tok))
return ExprUsage::NotUsed;
if (tok->astParent()->isConstOp())
return ExprUsage::NotUsed;
if (tok->astParent()->isCast())
return ExprUsage::NotUsed;
}
if (indirect == 0) {
if (Token::Match(tok->astParent(), "%cop%|%assign%|++|--") && !Token::simpleMatch(tok->astParent(), "=") &&
!tok->astParent()->isUnaryOp("&"))
return ExprUsage::Used;
if (Token::simpleMatch(tok->astParent(), "=") && astIsRHS(tok))
return ExprUsage::Used;
// Function call or index
if (Token::Match(tok->astParent(), "(|[") && !tok->astParent()->isCast() &&
(astIsLHS(tok) || Token::simpleMatch(tok->astParent(), "( )")))
return ExprUsage::Used;
}
return getFunctionUsage(tok, indirect, settings);
}
static void getLHSVariablesRecursive(std::vector<const Variable*>& vars, const Token* tok)
{
if (!tok)

4
lib/astutils.h
View File

@ -392,6 +392,10 @@ bool isCPPCast(const Token* tok);
bool isConstVarExpression(const Token* tok, std::function<bool(const Token*)> skipPredicate = nullptr);
enum class ExprUsage { None, NotUsed, PassedByReference, Used, Inconclusive };
ExprUsage getExprUsage(const Token* tok, int indirect, const Settings* settings);
const Variable *getLHSVariable(const Token *tok);
const Token* getLHSVariableToken(const Token* tok);

29
lib/checkother.cpp
View File

@ -3228,6 +3228,8 @@ void CheckOther::checkAccessOfMovedVariable()
scopeStart = memberInitializationStart;
}
for (const Token* tok = scopeStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (!tok->astParent())
continue;
const ValueFlow::Value * movedValue = tok->getMovedValue();
if (!movedValue || movedValue->moveKind == ValueFlow::Value::MoveKind::NonMovedVariable)
continue;
@ -3242,13 +3244,13 @@ void CheckOther::checkAccessOfMovedVariable()
else
inconclusive = true;
} else {
const bool variableChanged = isVariableChangedByFunctionCall(tok, 0, mSettings, &inconclusive);
accessOfMoved = !variableChanged && checkUninitVar.isVariableUsage(tok, false, CheckUninitVar::NO_ALLOC);
if (inconclusive) {
accessOfMoved = !isMovedParameterAllowedForInconclusiveFunction(tok);
if (accessOfMoved)
inconclusive = false;
}
const ExprUsage usage = getExprUsage(tok, 0, mSettings);
if (usage == ExprUsage::Used)
accessOfMoved = true;
if (usage == ExprUsage::PassedByReference)
accessOfMoved = !isVariableChangedByFunctionCall(tok, 0, mSettings, &inconclusive);
else if (usage == ExprUsage::Inconclusive)
inconclusive = true;
}
if (accessOfMoved || (inconclusive && reportInconclusive))
accessMovedError(tok, tok->str(), movedValue, inconclusive || movedValue->isInconclusive());
@ -3256,19 +3258,6 @@ void CheckOther::checkAccessOfMovedVariable()
}
}
bool CheckOther::isMovedParameterAllowedForInconclusiveFunction(const Token * tok)
{
if (Token::simpleMatch(tok->tokAt(-4), "std :: move ("))
return false;
const Token * tokAtM2 = tok->tokAt(-2);
if (Token::simpleMatch(tokAtM2, "> (") && tokAtM2->link()) {
const Token * leftAngle = tokAtM2->link();
if (Token::simpleMatch(leftAngle->tokAt(-3), "std :: forward <"))
return false;
}
return true;
}
void CheckOther::accessMovedError(const Token *tok, const std::string &varname, const ValueFlow::Value *value, bool inconclusive)
{
if (!tok) {

1
lib/checkother.h
View File

@ -275,7 +275,6 @@ private:
void raceAfterInterlockedDecrementError(const Token* tok);
void unusedLabelError(const Token* tok, bool inSwitch, bool hasIfdef);
void unknownEvaluationOrder(const Token* tok);
static bool isMovedParameterAllowedForInconclusiveFunction(const Token * tok);
void accessMovedError(const Token *tok, const std::string &varname, const ValueFlow::Value *value, bool inconclusive);
void funcArgNamesDifferent(const std::string & functionName, nonneg int index, const Token* declaration, const Token* definition);
void funcArgOrderDifferent(const std::string & functionName, const Token * declaration, const Token * definition, const std::vector<const Token*> & declarations, const std::vector<const Token*> & definitions);

45
lib/checkuninitvar.cpp
View File

@ -1561,51 +1561,6 @@ void CheckUninitVar::uninitStructMemberError(const Token *tok, const std::string
"$symbol:" + membername + "\nUninitialized struct member: $symbol", CWE_USE_OF_UNINITIALIZED_VARIABLE, Certainty::normal);
}
enum class ExprUsage { None, NotUsed, PassedByReference, Used };
static ExprUsage getFunctionUsage(const Token* tok, int indirect, const Settings* settings)
{
const bool addressOf = tok->astParent() && tok->astParent()->isUnaryOp("&");
int argnr;
const Token* ftok = getTokenArgumentFunction(tok, argnr);
if (!ftok)
return ExprUsage::None;
if (ftok->function()) {
std::vector<const Variable*> args = getArgumentVars(ftok, argnr);
for (const Variable* arg : args) {
if (!arg)
continue;
if (arg->isReference())
return ExprUsage::PassedByReference;
}
} else {
const bool isnullbad = settings->library.isnullargbad(ftok, argnr + 1);
if (indirect == 0 && astIsPointer(tok) && !addressOf && isnullbad)
return ExprUsage::Used;
bool hasIndirect = false;
const bool isuninitbad = settings->library.isuninitargbad(ftok, argnr + 1, indirect, &hasIndirect);
if (isuninitbad && (!addressOf || isnullbad))
return ExprUsage::Used;
}
return ExprUsage::None;
}
static ExprUsage getExprUsage(const Token* tok, int indirect, const Settings* settings)
{
if (indirect > 0 && tok->astParent()) {
if (Token::Match(tok->astParent(), "%assign%") && astIsRhs(tok))
return ExprUsage::NotUsed;
if (tok->astParent()->isConstOp())
return ExprUsage::NotUsed;
if (tok->astParent()->isCast())
return ExprUsage::NotUsed;
}
if (indirect == 0 && Token::Match(tok->astParent(), "%cop%|%assign%|++|--") && tok->astParent()->str() != "=")
return ExprUsage::Used;
return getFunctionUsage(tok, indirect, settings);
}
static bool isLeafDot(const Token* tok)
{
if (!tok)

11
test/testother.cpp
View File

@ -259,6 +259,7 @@ private:
TEST_CASE(partiallyMoved);
TEST_CASE(moveAndLambda);
TEST_CASE(moveInLoop);
TEST_CASE(moveCallback);
TEST_CASE(forwardAndUsed);
TEST_CASE(funcArgNamesDifferent);
@ -9958,6 +9959,16 @@ private:
ASSERT_EQUALS("[test.cpp:4]: (warning) Access of moved variable 'l'.\n", errout.str());
}
void moveCallback()
{
check("bool f(std::function<void()>&& callback);\n"
"void func(std::function<void()> callback) {\n"
" if(!f(std::move(callback)))\n"
" callback();\n"
"}\n");
ASSERT_EQUALS("[test.cpp:4]: (warning) Access of moved variable 'callback'.\n", errout.str());
}
void forwardAndUsed() {
Settings keepTemplates;
keepTemplates.checkUnusedTemplates = true;