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ValueFlow: Limit the combinations of arguments passed to subfunctions in normal analysis #4950

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Merged
danmar merged 1 commit into from
Apr 12, 2023
Merged

ValueFlow: Limit the combinations of arguments passed to subfunctions in normal analysis #4950

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2 changes: 2 additions & 0 deletions lib/settings.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -229,10 +229,12 @@ void Settings::setCheckLevelExhaustive()
{
// Checking can take a little while. ~ 10 times slower than normal analysis is OK.
performanceValueFlowMaxIfCount = -1;
performanceValueFlowMaxSubFunctionArgs = 256;
}

void Settings::setCheckLevelNormal()
{
// Checking should finish in reasonable time.
performanceValueFlowMaxSubFunctionArgs = 8;
performanceValueFlowMaxIfCount = 100;
}
3 changes: 3 additions & 0 deletions lib/settings.h
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Expand Up @@ -252,6 +252,9 @@ class CPPCHECKLIB Settings {
/** @brief --performance-valueflow-max-if-count=C */
int performanceValueFlowMaxIfCount;

/** @brief max number of sets of arguments to pass to subfuncions in valueflow */
int performanceValueFlowMaxSubFunctionArgs;

/** @brief plist output (--plist-output=<dir>) */
std::string plistOutput;

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23 changes: 17 additions & 6 deletions lib/valueflow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7244,7 +7244,7 @@ struct MultiValueFlowAnalyzer : ValueFlowAnalyzer {
};

template<class Key, class F>
bool productParams(const std::unordered_map<Key, std::list<ValueFlow::Value>>& vars, F f)
bool productParams(const Settings* settings, const std::unordered_map<Key, std::list<ValueFlow::Value>>& vars, F f)
{
using Args = std::vector<std::unordered_map<Key, ValueFlow::Value>>;
Args args(1);
Expand All @@ -7254,9 +7254,15 @@ bool productParams(const std::unordered_map<Key, std::list<ValueFlow::Value>>& v
continue;
args.back()[p.first] = p.second.front();
}
bool bail = false;
int max = 8;
if (settings)
max = settings->performanceValueFlowMaxSubFunctionArgs;
for (const auto& p:vars) {
if (args.size() > 256)
return false;
if (args.size() > max) {
bail = true;
break;
}
if (p.second.empty())
continue;
std::for_each(std::next(p.second.begin()), p.second.end(), [&](const ValueFlow::Value& value) {
Expand All @@ -7279,6 +7285,11 @@ bool productParams(const std::unordered_map<Key, std::list<ValueFlow::Value>>& v
});
}

if (args.size() > max) {
bail = true;
args.resize(max);
}

for (const auto& arg:args) {
if (arg.empty())
continue;
Expand All @@ -7290,7 +7301,7 @@ bool productParams(const std::unordered_map<Key, std::list<ValueFlow::Value>>& v
continue;
f(arg);
}
return true;
return !bail;
}

static void valueFlowInjectParameter(TokenList* tokenlist,
Expand All @@ -7300,7 +7311,7 @@ static void valueFlowInjectParameter(TokenList* tokenlist,
const Scope* functionScope,
const std::unordered_map<const Variable*, std::list<ValueFlow::Value>>& vars)
{
const bool r = productParams(vars, [&](const std::unordered_map<const Variable*, ValueFlow::Value>& arg) {
const bool r = productParams(&settings, vars, [&](const std::unordered_map<const Variable*, ValueFlow::Value>& arg) {
MultiValueFlowAnalyzer a(arg, tokenlist, &settings, symboldatabase);
valueFlowGenericForward(const_cast<Token*>(functionScope->bodyStart), functionScope->bodyEnd, a, settings);
});
Expand Down Expand Up @@ -7431,7 +7442,7 @@ static void valueFlowLibraryFunction(Token *tok, const std::string &returnValue,
}
if (returnValue.find("arg") != std::string::npos && argValues.empty())
return;
productParams(argValues, [&](const std::unordered_map<nonneg int, ValueFlow::Value>& arg) {
productParams(settings, argValues, [&](const std::unordered_map<nonneg int, ValueFlow::Value>& arg) {
ValueFlow::Value value = evaluateLibraryFunction(arg, returnValue, settings);
if (value.isUninitValue())
return;
Expand Down