cppcheck/lib/checkmemoryleak.cpp

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/*
* Cppcheck - A tool for static C/C++ code analysis
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* Copyright (C) 2007-2023 Cppcheck team.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "checkmemoryleak.h"
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#include "astutils.h"
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#include "errorlogger.h"
#include "errortypes.h"
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#include "library.h"
#include "mathlib.h"
#include "platform.h"
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#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
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#include "tokenize.h"
#include <algorithm>
#include <utility>
#include <vector>
//---------------------------------------------------------------------------
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// Register this check class (by creating a static instance of it)
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namespace {
CheckMemoryLeakInFunction instance1;
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CheckMemoryLeakInClass instance2;
CheckMemoryLeakStructMember instance3;
CheckMemoryLeakNoVar instance4;
}
// CWE ID used:
static const CWE CWE398(398U); // Indicator of Poor Code Quality
static const CWE CWE401(401U); // Improper Release of Memory Before Removing Last Reference ('Memory Leak')
static const CWE CWE771(771U); // Missing Reference to Active Allocated Resource
static const CWE CWE772(772U); // Missing Release of Resource after Effective Lifetime
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//---------------------------------------------------------------------------
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CheckMemoryLeak::AllocType CheckMemoryLeak::getAllocationType(const Token *tok2, nonneg int varid, std::list<const Function*> *callstack) const
{
// What we may have...
// * var = (char *)malloc(10);
// * var = new char[10];
// * var = strdup("hello");
// * var = strndup("hello", 3);
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if (tok2 && tok2->str() == "(") {
tok2 = tok2->link();
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tok2 = tok2 ? tok2->next() : nullptr;
}
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if (!tok2)
return No;
if (tok2->str() == "::")
tok2 = tok2->next();
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if (!tok2->isName())
return No;
if (!Token::Match(tok2, "%name% ::|. %type%")) {
// Using realloc..
AllocType reallocType = getReallocationType(tok2, varid);
if (reallocType != No)
return reallocType;
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if (mTokenizer_->isCPP() && tok2->str() == "new") {
if (tok2->strAt(1) == "(" && !Token::Match(tok2->next(),"( std| ::| nothrow )"))
return No;
if (tok2->astOperand1() && (tok2->astOperand1()->str() == "[" || (tok2->astOperand1()->astOperand1() && tok2->astOperand1()->astOperand1()->str() == "[")))
return NewArray;
const Token *typeTok = tok2->next();
while (Token::Match(typeTok, "%name% :: %name%"))
typeTok = typeTok->tokAt(2);
const Scope* classScope = nullptr;
if (typeTok->type() && typeTok->type()->isClassType()) {
classScope = typeTok->type()->classScope;
} else if (typeTok->function() && typeTok->function()->isConstructor()) {
classScope = typeTok->function()->nestedIn;
}
if (classScope && classScope->numConstructors > 0)
return No;
return New;
}
if (mSettings_->hasLib("posix")) {
if (Token::Match(tok2, "open|openat|creat|mkstemp|mkostemp|socket (")) {
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// simple sanity check of function parameters..
// TODO: Make such check for all these functions
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const int num = numberOfArguments(tok2);
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if (tok2->str() == "open" && num != 2 && num != 3)
return No;
// is there a user function with this name?
if (tok2->function())
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return No;
return Fd;
}
if (Token::simpleMatch(tok2, "popen ("))
return Pipe;
}
// Does tok2 point on a Library allocation function?
const int alloctype = mSettings_->library.getAllocId(tok2, -1);
if (alloctype > 0) {
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if (alloctype == mSettings_->library.deallocId("free"))
return Malloc;
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if (alloctype == mSettings_->library.deallocId("fclose"))
return File;
return Library::ismemory(alloctype) ? OtherMem : OtherRes;
}
}
while (Token::Match(tok2,"%name% ::|. %type%"))
tok2 = tok2->tokAt(2);
// User function
const Function* func = tok2->function();
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if (func == nullptr)
return No;
// Prevent recursion
if (callstack && std::find(callstack->cbegin(), callstack->cend(), func) != callstack->cend())
return No;
std::list<const Function*> cs;
if (!callstack)
callstack = &cs;
callstack->push_back(func);
return functionReturnType(func, callstack);
}
CheckMemoryLeak::AllocType CheckMemoryLeak::getReallocationType(const Token *tok2, nonneg int varid) const
{
// What we may have...
// * var = (char *)realloc(..;
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if (tok2 && tok2->str() == "(") {
tok2 = tok2->link();
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tok2 = tok2 ? tok2->next() : nullptr;
}
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if (!tok2)
return No;
if (!Token::Match(tok2, "%name% ("))
return No;
const Library::AllocFunc *f = mSettings_->library.getReallocFuncInfo(tok2);
if (!(f && f->reallocArg > 0 && f->reallocArg <= numberOfArguments(tok2)))
return No;
const auto args = getArguments(tok2);
if (args.size() < (f->reallocArg))
return No;
const Token* arg = args.at(f->reallocArg - 1);
while (arg && arg->isCast())
arg = arg->astOperand1();
while (arg && arg->isUnaryOp("*"))
arg = arg->astOperand1();
if (varid > 0 && !Token::Match(arg, "%varid% [,)]", varid))
return No;
const int realloctype = mSettings_->library.getReallocId(tok2, -1);
if (realloctype > 0) {
if (realloctype == mSettings_->library.deallocId("free"))
return Malloc;
if (realloctype == mSettings_->library.deallocId("fclose"))
return File;
return Library::ismemory(realloctype) ? OtherMem : OtherRes;
}
return No;
}
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CheckMemoryLeak::AllocType CheckMemoryLeak::getDeallocationType(const Token *tok, nonneg int varid) const
{
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if (mTokenizer_->isCPP() && tok->str() == "delete" && tok->astOperand1()) {
const Token* vartok = tok->astOperand1();
if (Token::Match(vartok, ".|::"))
vartok = vartok->astOperand2();
if (vartok && vartok->varId() == varid) {
if (tok->strAt(1) == "[")
return NewArray;
return New;
}
}
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if (tok->str() == "::")
tok = tok->next();
if (Token::Match(tok, "%name% (")) {
if (Token::simpleMatch(tok, "fcloseall ( )"))
return File;
int argNr = 1;
for (const Token* tok2 = tok->tokAt(2); tok2; tok2 = tok2->nextArgument()) {
const Token* vartok = tok2;
while (Token::Match(vartok, "%name% .|::"))
vartok = vartok->tokAt(2);
if (Token::Match(vartok, "%varid% )|,|-", varid)) {
if (tok->str() == "realloc" && Token::simpleMatch(vartok->next(), ", 0 )"))
return Malloc;
if (mSettings_->hasLib("posix")) {
if (tok->str() == "close")
return Fd;
if (tok->str() == "pclose")
return Pipe;
}
// Does tok point on a Library deallocation function?
const int dealloctype = mSettings_->library.getDeallocId(tok, argNr);
if (dealloctype > 0) {
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if (dealloctype == mSettings_->library.deallocId("free"))
return Malloc;
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if (dealloctype == mSettings_->library.deallocId("fclose"))
return File;
return Library::ismemory(dealloctype) ? OtherMem : OtherRes;
}
}
argNr++;
}
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}
return No;
}
bool CheckMemoryLeak::isReopenStandardStream(const Token *tok) const
{
if (getReallocationType(tok, 0) == File) {
const Library::AllocFunc *f = mSettings_->library.getReallocFuncInfo(tok);
if (f && f->reallocArg > 0 && f->reallocArg <= numberOfArguments(tok)) {
const Token* arg = getArguments(tok).at(f->reallocArg - 1);
if (Token::Match(arg, "stdin|stdout|stderr"))
return true;
}
}
return false;
}
bool CheckMemoryLeak::isOpenDevNull(const Token *tok) const
{
if (mSettings_->hasLib("posix") && tok->str() == "open" && numberOfArguments(tok) == 2) {
const Token* arg = getArguments(tok).at(0);
if (Token::simpleMatch(arg, "\"/dev/null\""))
return true;
}
return false;
}
//--------------------------------------------------------------------------
//--------------------------------------------------------------------------
void CheckMemoryLeak::memoryLeak(const Token *tok, const std::string &varname, AllocType alloctype) const
{
if (alloctype == CheckMemoryLeak::File ||
alloctype == CheckMemoryLeak::Pipe ||
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alloctype == CheckMemoryLeak::Fd ||
alloctype == CheckMemoryLeak::OtherRes)
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resourceLeakError(tok, varname);
else
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memleakError(tok, varname);
}
//---------------------------------------------------------------------------
void CheckMemoryLeak::reportErr(const Token *tok, Severity severity, const std::string &id, const std::string &msg, const CWE &cwe) const
{
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std::list<const Token *> callstack;
if (tok)
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callstack.push_back(tok);
reportErr(callstack, severity, id, msg, cwe);
}
void CheckMemoryLeak::reportErr(const std::list<const Token *> &callstack, Severity severity, const std::string &id, const std::string &msg, const CWE &cwe) const
{
const ErrorMessage errmsg(callstack, mTokenizer_ ? &mTokenizer_->list : nullptr, severity, id, msg, cwe, Certainty::normal);
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if (mErrorLogger_)
mErrorLogger_->reportErr(errmsg);
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else
Check::writeToErrorList(errmsg);
}
void CheckMemoryLeak::memleakError(const Token *tok, const std::string &varname) const
{
reportErr(tok, Severity::error, "memleak", "$symbol:" + varname + "\nMemory leak: $symbol", CWE(401U));
}
void CheckMemoryLeak::memleakUponReallocFailureError(const Token *tok, const std::string &reallocfunction, const std::string &varname) const
{
reportErr(tok, Severity::error, "memleakOnRealloc", "$symbol:" + varname + "\nCommon " + reallocfunction + " mistake: \'$symbol\' nulled but not freed upon failure", CWE(401U));
}
void CheckMemoryLeak::resourceLeakError(const Token *tok, const std::string &varname) const
{
std::string errmsg("Resource leak");
if (!varname.empty())
errmsg = "$symbol:" + varname + '\n' + errmsg + ": $symbol";
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reportErr(tok, Severity::error, "resourceLeak", errmsg, CWE(775U));
}
void CheckMemoryLeak::deallocuseError(const Token *tok, const std::string &varname) const
{
reportErr(tok, Severity::error, "deallocuse", "$symbol:" + varname + "\nDereferencing '$symbol' after it is deallocated / released", CWE(416U));
}
void CheckMemoryLeak::mismatchAllocDealloc(const std::list<const Token *> &callstack, const std::string &varname) const
{
reportErr(callstack, Severity::error, "mismatchAllocDealloc", "$symbol:" + varname + "\nMismatching allocation and deallocation: $symbol", CWE(762U));
}
CheckMemoryLeak::AllocType CheckMemoryLeak::functionReturnType(const Function* func, std::list<const Function*> *callstack) const
{
if (!func || !func->hasBody() || !func->functionScope)
return No;
// Get return pointer..
const Variable* var = nullptr;
for (const Token *tok2 = func->functionScope->bodyStart; tok2 != func->functionScope->bodyEnd; tok2 = tok2->next()) {
if (const Token *endOfLambda = findLambdaEndToken(tok2))
tok2 = endOfLambda;
if (tok2->str() == "{" && !tok2->scope()->isExecutable())
tok2 = tok2->link();
if (tok2->str() == "return") {
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const AllocType allocType = getAllocationType(tok2->next(), 0, callstack);
if (allocType != No)
return allocType;
if (tok2->scope() != func->functionScope || !tok2->astOperand1())
return No;
const Token* tok = tok2->astOperand1();
if (Token::Match(tok, ".|::"))
tok = tok->astOperand2() ? tok->astOperand2() : tok->astOperand1();
if (tok)
var = tok->variable();
break;
}
}
// Not returning pointer value..
if (!var)
return No;
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// If variable is not local then alloctype shall be "No"
// Todo: there can be false negatives about mismatching allocation/deallocation.
// => Generate "alloc ; use ;" if variable is not local?
if (!var->isLocal() || var->isStatic())
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return No;
// Check if return pointer is allocated..
AllocType allocType = No;
nonneg int const varid = var->declarationId();
for (const Token* tok = func->functionScope->bodyStart; tok != func->functionScope->bodyEnd; tok = tok->next()) {
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if (Token::Match(tok, "%varid% =", varid)) {
allocType = getAllocationType(tok->tokAt(2), varid, callstack);
}
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if (Token::Match(tok, "= %varid% ;", varid)) {
return No;
}
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if (!mTokenizer_->isC() && Token::Match(tok, "[(,] %varid% [,)]", varid)) {
return No;
}
if (Token::Match(tok, "[(,] & %varid% [.,)]", varid)) {
return No;
}
if (Token::Match(tok, "[;{}] %varid% .", varid)) {
return No;
}
if (allocType == No && tok->str() == "return")
return No;
}
return allocType;
}
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static bool notvar(const Token *tok, nonneg int varid)
{
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if (!tok)
return false;
if (Token::Match(tok, "&&|;"))
return notvar(tok->astOperand1(),varid) || notvar(tok->astOperand2(),varid);
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if (tok->str() == "(" && Token::Match(tok->astOperand1(), "UNLIKELY|LIKELY"))
return notvar(tok->astOperand2(), varid);
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const Token *vartok = astIsVariableComparison(tok, "==", "0");
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return vartok && (vartok->varId() == varid);
}
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static bool ifvar(const Token *tok, nonneg int varid, const std::string &comp, const std::string &rhs)
{
if (!Token::simpleMatch(tok, "if ("))
return false;
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const Token *condition = tok->next()->astOperand2();
if (condition && condition->str() == "(" && Token::Match(condition->astOperand1(), "UNLIKELY|LIKELY"))
condition = condition->astOperand2();
if (!condition || condition->str() == "&&")
return false;
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const Token *vartok = astIsVariableComparison(condition, comp, rhs);
return (vartok && vartok->varId() == varid);
}
//---------------------------------------------------------------------------
// Check for memory leaks due to improper realloc() usage.
// Below, "a" may be set to null without being freed if realloc() cannot
// allocate the requested memory:
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// a = malloc(10); a = realloc(a, 100);
//---------------------------------------------------------------------------
void CheckMemoryLeakInFunction::checkReallocUsage()
{
logChecker("CheckMemoryLeakInFunction::checkReallocUsage");
// only check functions
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const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
// Search for the "var = realloc(var, 100" pattern within this function
for (const Token *tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (tok->varId() > 0 && Token::Match(tok, "%name% =")) {
// Get the parenthesis in "realloc("
const Token* parTok = tok->next()->astOperand2();
// Skip casts
while (parTok && parTok->isCast())
parTok = parTok->astOperand1();
if (!parTok)
continue;
const Token *const reallocTok = parTok->astOperand1();
if (!reallocTok)
continue;
const Library::AllocFunc* f = mSettings->library.getReallocFuncInfo(reallocTok);
if (!(f && f->arg == -1 && mSettings->library.isnotnoreturn(reallocTok)))
continue;
const AllocType allocType = getReallocationType(reallocTok, tok->varId());
if (!((allocType == Malloc || allocType == OtherMem)))
continue;
const Token* arg = getArguments(reallocTok).at(f->reallocArg - 1);
while (arg && arg->isCast())
arg = arg->astOperand1();
const Token* tok2 = tok;
while (arg && arg->isUnaryOp("*") && tok2 && tok2->astParent() && tok2->astParent()->isUnaryOp("*")) {
arg = arg->astOperand1();
tok2 = tok2->astParent();
}
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if (!arg || !tok2)
continue;
if (!(tok->varId() == arg->varId() && tok->variable() && !tok->variable()->isArgument()))
continue;
// Check that another copy of the pointer wasn't saved earlier in the function
if (Token::findmatch(scope->bodyStart, "%name% = %varid% ;", tok, tok->varId()) ||
Token::findmatch(scope->bodyStart, "[{};] %varid% = *| %var% .| %var%| [;=]", tok, tok->varId()))
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continue;
// Check if the argument is known to be null, which means it is not a memory leak
if (arg->hasKnownIntValue() && arg->getKnownIntValue() == 0) {
continue;
}
const Token* tokEndRealloc = reallocTok->linkAt(1);
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// Check that the allocation isn't followed immediately by an 'if (!var) { error(); }' that might handle failure
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if (Token::simpleMatch(tokEndRealloc->next(), "; if (") &&
notvar(tokEndRealloc->tokAt(3)->astOperand2(), tok->varId())) {
const Token* tokEndBrace = tokEndRealloc->linkAt(3)->linkAt(1);
if (tokEndBrace && mTokenizer->isScopeNoReturn(tokEndBrace))
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continue;
}
memleakUponReallocFailureError(tok, reallocTok->str(), tok->str());
}
}
}
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// Checks for memory leaks in classes..
//---------------------------------------------------------------------------
void CheckMemoryLeakInClass::check()
{
logChecker("CheckMemoryLeakInClass::check");
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
// only check classes and structures
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for (const Scope * scope : symbolDatabase->classAndStructScopes) {
for (const Variable &var : scope->varlist) {
if (!var.isStatic() && (var.isPointer() || var.isPointerArray())) {
// allocation but no deallocation of private variables in public function..
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const Token *tok = var.typeStartToken();
// Either it is of standard type or a non-derived type
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if (tok->isStandardType() || (var.type() && var.type()->derivedFrom.empty())) {
if (var.isPrivate())
checkPublicFunctions(scope, var.nameToken());
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variable(scope, var.nameToken());
}
}
}
}
}
void CheckMemoryLeakInClass::variable(const Scope *scope, const Token *tokVarname)
{
const std::string& varname = tokVarname->str();
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const int varid = tokVarname->varId();
const std::string& classname = scope->className;
// Check if member variable has been allocated and deallocated..
CheckMemoryLeak::AllocType memberAlloc = CheckMemoryLeak::No;
CheckMemoryLeak::AllocType memberDealloc = CheckMemoryLeak::No;
bool allocInConstructor = false;
bool deallocInDestructor = false;
// Inspect member functions
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for (const Function &func : scope->functionList) {
const bool constructor = func.isConstructor();
const bool destructor = func.isDestructor();
if (!func.hasBody()) {
Fix defaulted and deleted functions (#4540) * Fix 9392, but for destructors: out-of-line defaulted destructors skipped everything after Context: ``` struct S { ~S(); }; S::~S() = default; void g() { int j; ++j; } ``` Everything after `S::~S() = default;` was skipped, so the uninitialized variables in g() weren't found. Out-of-line destructors are useful e.g. when you have a forward declared unique_ptr in the .h, and `= default` the destructor in the .cpp, so only the cpp needs to know the header for destructing your unique_ptr (like in the pImpl-idiom) * Fix unit test, by correctly fixing 10789 Previous commit broke this test, but also provided the tools for a cleaner fix * Document current behaviour * Rewrite control flow * Fix deleted functions, which skipped everything after `a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction, which sets tok to nullptr, effectively skipping to the end of the stream. * Remove troublesome nullptr, which skips every analysis afterwards It was introduced in 0746c241 to fix a memory leak. But setting tok to nullptr, effectively skipping to the end, seems not needed. Previous commits fixes prevented some cases where you could enter the `else`. This commit is more of a fall back. * fixup! Fix deleted functions, which skipped everything after `a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction, which sets tok to nullptr, effectively skipping to the end of the stream. * fixup! Fix deleted functions, which skipped everything after `a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction, which sets tok to nullptr, effectively skipping to the end of the stream. * Make it heard when encountering unexpected syntax/tokens Co-authored-by: Gerbo Engels <gerbo.engels@ortec-finance.com>
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if (destructor && !func.isDefault()) { // implementation for destructor is not seen and not defaulted => assume it deallocates all variables properly
deallocInDestructor = true;
memberDealloc = CheckMemoryLeak::Many;
}
continue;
}
bool body = false;
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const Token *end = func.functionScope->bodyEnd;
for (const Token *tok = func.arg->link(); tok != end; tok = tok->next()) {
if (tok == func.functionScope->bodyStart)
body = true;
else {
if (!body) {
if (!Token::Match(tok, ":|, %varid% (", varid))
continue;
}
// Allocate..
if (!body || Token::Match(tok, "%varid% =|[", varid)) {
// var1 = var2 = ...
// bail out
if (tok->strAt(-1) == "=")
return;
// Foo::var1 = ..
// bail out when not same class
if (tok->strAt(-1) == "::" &&
tok->strAt(-2) != scope->className)
return;
const Token* allocTok = tok->tokAt(body ? 2 : 3);
if (tok->astParent() && tok->astParent()->str() == "[" && tok->astParent()->astParent())
allocTok = tok->astParent()->astParent()->astOperand2();
AllocType alloc = getAllocationType(allocTok, 0);
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if (alloc != CheckMemoryLeak::No) {
if (constructor)
allocInConstructor = true;
if (memberAlloc != No && memberAlloc != alloc)
alloc = CheckMemoryLeak::Many;
if (alloc != CheckMemoryLeak::Many && memberDealloc != CheckMemoryLeak::No && memberDealloc != CheckMemoryLeak::Many && memberDealloc != alloc) {
mismatchAllocDealloc({tok}, classname + "::" + varname);
}
memberAlloc = alloc;
}
}
if (!body)
continue;
// Deallocate..
AllocType dealloc = getDeallocationType(tok, varid);
// some usage in the destructor => assume it's related
// to deallocation
if (destructor && tok->str() == varname)
dealloc = CheckMemoryLeak::Many;
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if (dealloc != CheckMemoryLeak::No) {
if (destructor)
deallocInDestructor = true;
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if (dealloc != CheckMemoryLeak::Many && memberAlloc != CheckMemoryLeak::No && memberAlloc != Many && memberAlloc != dealloc) {
mismatchAllocDealloc({tok}, classname + "::" + varname);
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}
// several types of allocation/deallocation?
if (memberDealloc != CheckMemoryLeak::No && memberDealloc != dealloc)
dealloc = CheckMemoryLeak::Many;
memberDealloc = dealloc;
}
// Function call .. possible deallocation
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else if (Token::Match(tok->previous(), "[{};] %name% (") && !tok->isKeyword() && !mSettings->library.isLeakIgnore(tok->str())) {
return;
}
}
}
}
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if (allocInConstructor && !deallocInDestructor) {
unsafeClassError(tokVarname, classname, classname + "::" + varname /*, memberAlloc*/);
} else if (memberAlloc != CheckMemoryLeak::No && memberDealloc == CheckMemoryLeak::No) {
unsafeClassError(tokVarname, classname, classname + "::" + varname /*, memberAlloc*/);
}
}
void CheckMemoryLeakInClass::unsafeClassError(const Token *tok, const std::string &classname, const std::string &varname)
{
if (!mSettings->severity.isEnabled(Severity::style))
return;
reportError(tok, Severity::style, "unsafeClassCanLeak",
"$symbol:" + classname + "\n"
"$symbol:" + varname + "\n"
"Class '" + classname + "' is unsafe, '" + varname + "' can leak by wrong usage.\n"
"The class '" + classname + "' is unsafe, wrong usage can cause memory/resource leaks for '" + varname + "'. This can for instance be fixed by adding proper cleanup in the destructor.", CWE398, Certainty::normal);
}
void CheckMemoryLeakInClass::checkPublicFunctions(const Scope *scope, const Token *classtok)
{
// Check that public functions deallocate the pointers that they allocate.
// There is no checking how these functions are used and therefore it
// isn't established if there is real leaks or not.
if (!mSettings->severity.isEnabled(Severity::warning))
return;
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const int varid = classtok->varId();
// Parse public functions..
// If they allocate member variables, they should also deallocate
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for (const Function &func : scope->functionList) {
if ((func.type == Function::eFunction || func.type == Function::eOperatorEqual) &&
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func.access == AccessControl::Public && func.hasBody()) {
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const Token *tok2 = func.functionScope->bodyStart->next();
if (Token::Match(tok2, "%varid% =", varid)) {
const CheckMemoryLeak::AllocType alloc = getAllocationType(tok2->tokAt(2), varid);
if (alloc != CheckMemoryLeak::No)
publicAllocationError(tok2, tok2->str());
} else if (Token::Match(tok2, "%type% :: %varid% =", varid) &&
tok2->str() == scope->className) {
const CheckMemoryLeak::AllocType alloc = getAllocationType(tok2->tokAt(4), varid);
if (alloc != CheckMemoryLeak::No)
publicAllocationError(tok2, tok2->strAt(2));
}
}
}
}
void CheckMemoryLeakInClass::publicAllocationError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::warning, "publicAllocationError", "$symbol:" + varname + "\nPossible leak in public function. The pointer '$symbol' is not deallocated before it is allocated.", CWE398, Certainty::normal);
}
void CheckMemoryLeakStructMember::check()
{
if (mSettings->clang)
return;
logChecker("CheckMemoryLeakStructMember::check");
const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Variable* var : symbolDatabase->variableList()) {
if (!var || (!var->isLocal() && !(var->isArgument() && var->scope())) || var->isStatic())
continue;
if (var->isReference() || (var->valueType() && var->valueType()->pointer > 1))
continue;
if (var->typeEndToken()->isStandardType())
continue;
checkStructVariable(var);
}
}
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bool CheckMemoryLeakStructMember::isMalloc(const Variable *variable) const
{
if (!variable)
return false;
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const int declarationId(variable->declarationId());
bool alloc = false;
for (const Token *tok2 = variable->nameToken(); tok2 && tok2 != variable->scope()->bodyEnd; tok2 = tok2->next()) {
if (Token::Match(tok2, "= %varid% [;=]", declarationId))
return false;
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if (Token::Match(tok2, "%varid% = %name% (", declarationId) && mSettings->library.getAllocFuncInfo(tok2->tokAt(2)))
alloc = true;
}
return alloc;
}
void CheckMemoryLeakStructMember::checkStructVariable(const Variable* const variable) const
{
if (!variable)
return;
// Is struct variable a pointer?
if (variable->isArrayOrPointer()) {
// Check that variable is allocated with malloc
if (!isMalloc(variable))
return;
} else if (!mTokenizer->isC() && (!variable->typeScope() || variable->typeScope()->getDestructor())) {
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// For non-C code a destructor might cleanup members
return;
}
// Check struct..
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int indentlevel2 = 0;
auto deallocInFunction = [this](const Token* tok, int structid) -> bool {
// Calling non-function / function that doesn't deallocate?
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if (tok->isKeyword() || mSettings->library.isLeakIgnore(tok->str()))
return false;
// Check if the struct is used..
bool deallocated = false;
const Token* const end = tok->linkAt(1);
for (const Token* tok2 = tok; tok2 != end; tok2 = tok2->next()) {
if (Token::Match(tok2, "[(,] &| %varid% [,)]", structid)) {
/** @todo check if the function deallocates the memory */
deallocated = true;
break;
}
if (Token::Match(tok2, "[(,] &| %varid% . %name% [,)]", structid)) {
/** @todo check if the function deallocates the memory */
deallocated = true;
break;
}
}
return deallocated;
};
// return { memberTok, rhsTok }
auto isMemberAssignment = [](const Token* varTok, int varId) -> std::pair<const Token*, const Token*> {
if (varTok->varId() != varId)
return {};
const Token* top = varTok;
while (top->astParent()) {
if (Token::Match(top->astParent(), "(|["))
return {};
top = top->astParent();
}
if (!Token::simpleMatch(top, "=") || !precedes(varTok, top))
return {};
const Token* dot = top->astOperand1();
while (dot && dot->str() != ".")
dot = dot->astOperand1();
if (!dot)
return {};
return { dot->astOperand2(), top->next() };
};
std::pair<const Token*, const Token*> assignToks;
const Token* tokStart = variable->nameToken();
if (variable->isArgument() && variable->scope())
tokStart = variable->scope()->bodyStart->next();
for (const Token *tok2 = tokStart; tok2 && tok2 != variable->scope()->bodyEnd; tok2 = tok2->next()) {
if (tok2->str() == "{")
++indentlevel2;
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else if (tok2->str() == "}") {
if (indentlevel2 == 0)
break;
--indentlevel2;
}
// Unknown usage of struct
/** @todo Check how the struct is used. Only bail out if necessary */
else if (Token::Match(tok2, "[(,] %varid% [,)]", variable->declarationId()))
break;
// Struct member is allocated => check if it is also properly deallocated..
else if ((assignToks = isMemberAssignment(tok2, variable->declarationId())).first && assignToks.first->varId()) {
if (getAllocationType(assignToks.second, assignToks.first->varId()) == AllocType::No)
continue;
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if (variable->isArgument() && variable->valueType() && variable->valueType()->type == ValueType::UNKNOWN_TYPE && assignToks.first->astParent()) {
const Token* accessTok = assignToks.first->astParent();
while (Token::simpleMatch(accessTok->astOperand1(), "."))
accessTok = accessTok->astOperand1();
if (Token::simpleMatch(accessTok, ".") && accessTok->originalName() == "->")
continue;
}
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const int structid(variable->declarationId());
const int structmemberid(assignToks.first->varId());
// This struct member is allocated.. check that it is deallocated
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int indentlevel3 = indentlevel2;
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for (const Token *tok3 = tok2; tok3; tok3 = tok3->next()) {
if (tok3->str() == "{")
++indentlevel3;
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else if (tok3->str() == "}") {
if (indentlevel3 == 0) {
memoryLeak(tok3, variable->name() + "." + tok2->strAt(2), Malloc);
break;
}
--indentlevel3;
}
// Deallocating the struct member..
else if (getDeallocationType(tok3, structmemberid) != AllocType::No) {
// If the deallocation happens at the base level, don't check this member anymore
if (indentlevel3 == 0)
break;
// deallocating and then returning from function in a conditional block =>
// skip ahead out of the block
bool ret = false;
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while (tok3) {
if (tok3->str() == "return")
ret = true;
else if (tok3->str() == "{" || tok3->str() == "}")
break;
tok3 = tok3->next();
}
if (!ret || !tok3 || tok3->str() != "}")
break;
--indentlevel3;
continue;
}
// Deallocating the struct..
else if (Token::Match(tok3, "%name% ( %varid% )", structid) && mSettings->library.getDeallocFuncInfo(tok3)) {
if (indentlevel2 == 0)
memoryLeak(tok3, variable->name() + "." + tok2->strAt(2), Malloc);
break;
}
// failed allocation => skip code..
else if (Token::simpleMatch(tok3, "if (") &&
notvar(tok3->next()->astOperand2(), structmemberid)) {
// Goto the ")"
tok3 = tok3->next()->link();
// make sure we have ") {".. it should be
if (!Token::simpleMatch(tok3, ") {"))
break;
// Goto the "}"
tok3 = tok3->next()->link();
}
// succeeded allocation
else if (ifvar(tok3, structmemberid, "!=", "0")) {
// goto the ")"
tok3 = tok3->next()->link();
// check if the variable is deallocated or returned..
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int indentlevel4 = 0;
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for (const Token *tok4 = tok3; tok4; tok4 = tok4->next()) {
if (tok4->str() == "{")
++indentlevel4;
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else if (tok4->str() == "}") {
--indentlevel4;
if (indentlevel4 == 0)
break;
} else if (Token::Match(tok4, "%name% ( %var% . %varid% )", structmemberid) && mSettings->library.getDeallocFuncInfo(tok4)) {
break;
}
}
// was there a proper deallocation?
if (indentlevel4 > 0)
break;
}
// Returning from function..
else if ((tok3->scope()->type != Scope::ScopeType::eLambda || tok3->scope() == variable->scope()) && tok3->str() == "return") {
// Returning from function without deallocating struct member?
if (!Token::Match(tok3, "return %varid% ;", structid) &&
!Token::Match(tok3, "return & %varid%", structid) &&
!(Token::Match(tok3, "return %varid% . %var%", structid) && tok3->tokAt(3)->varId() == structmemberid) &&
!(Token::Match(tok3, "return %name% (") && tok3->astOperand1() && deallocInFunction(tok3->astOperand1(), structid))) {
memoryLeak(tok3, variable->name() + "." + tok2->strAt(2), Malloc);
}
break;
}
// struct assignment..
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else if (Token::Match(tok3, "= %varid% ;", structid)) {
break;
} else if (Token::Match(tok3, "= %var% . %varid% ;", structmemberid)) {
break;
}
// goto isn't handled well.. bail out even though there might be leaks
else if (tok3->str() == "goto")
break;
// using struct in a function call..
else if (Token::Match(tok3, "%name% (")) {
if (deallocInFunction(tok3, structid))
break;
}
}
}
}
}
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void CheckMemoryLeakNoVar::check()
{
logChecker("CheckMemoryLeakNoVar::check");
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
// only check functions
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for (const Scope * scope : symbolDatabase->functionScopes) {
// Checks if a call to an allocation function like malloc() is made and its return value is not assigned.
checkForUnusedReturnValue(scope);
// Checks to see if a function is called with memory allocated for an argument that
// could be leaked if a function called for another argument throws.
checkForUnsafeArgAlloc(scope);
// Check for leaks where a the return value of an allocation function like malloc() is an input argument,
// for example f(malloc(1)), where f is known to not release the input argument.
checkForUnreleasedInputArgument(scope);
}
}
//---------------------------------------------------------------------------
// Checks if an input argument to a function is the return value of an allocation function
// like malloc(), and the function does not release it.
//---------------------------------------------------------------------------
void CheckMemoryLeakNoVar::checkForUnreleasedInputArgument(const Scope *scope)
{
// parse the executable scope until tok is reached...
for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
// allocating memory in parameter for function call..
if (tok->varId() || !Token::Match(tok, "%name% ("))
continue;
// check if the output of the function is assigned
const Token* tok2 = tok->next()->astParent();
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while (tok2 && (tok2->isCast() || Token::Match(tok2, "?|:")))
tok2 = tok2->astParent();
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if (Token::Match(tok2, "%assign%")) // TODO: check if function returns allocated resource
continue;
if (Token::simpleMatch(tok->astTop(), "return"))
continue;
const std::string& functionName = tok->str();
if ((mTokenizer->isCPP() && functionName == "delete") ||
functionName == "return")
continue;
if (Token::simpleMatch(tok->next()->astParent(), "(")) // passed to another function
continue;
if (!tok->isKeyword() && !tok->function() && !mSettings->library.isLeakIgnore(functionName))
continue;
const std::vector<const Token *> args = getArguments(tok);
int argnr = -1;
for (const Token* arg : args) {
++argnr;
if (arg->isOp() && !(tok->isKeyword() && arg->str() == "*")) // e.g. switch (*new int)
continue;
while (arg->astOperand1()) {
if (mTokenizer->isCPP() && Token::simpleMatch(arg, "new"))
break;
arg = arg->astOperand1();
}
const AllocType alloc = getAllocationType(arg, 0);
if (alloc == No)
continue;
if (alloc == New || alloc == NewArray) {
const Token* typeTok = arg->next();
bool bail = !typeTok->isStandardType() &&
!mSettings->library.detectContainerOrIterator(typeTok) &&
!mSettings->library.podtype(typeTok->expressionString());
if (bail && typeTok->type() && typeTok->type()->classScope &&
typeTok->type()->classScope->numConstructors == 0 &&
typeTok->type()->classScope->getDestructor() == nullptr) {
bail = false;
}
if (bail)
continue;
}
if (isReopenStandardStream(arg))
continue;
if (tok->function()) {
const Variable* argvar = tok->function()->getArgumentVar(argnr);
if (!argvar || !argvar->valueType())
continue;
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const MathLib::bigint argSize = argvar->valueType()->typeSize(mSettings->platform, /*p*/ true);
if (argSize <= 0 || argSize >= mSettings->platform.sizeof_pointer)
continue;
}
functionCallLeak(arg, arg->str(), functionName);
}
}
}
//---------------------------------------------------------------------------
// Checks if a call to an allocation function like malloc() is made and its return value is not assigned.
//---------------------------------------------------------------------------
void CheckMemoryLeakNoVar::checkForUnusedReturnValue(const Scope *scope)
{
for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
const bool isNew = mTokenizer->isCPP() && tok->str() == "new";
if (!isNew && !Token::Match(tok, "%name% ("))
continue;
if (tok->varId())
continue;
const AllocType allocType = getAllocationType(tok, 0);
if (allocType == No)
continue;
if (tok != tok->next()->astOperand1() && !isNew)
continue;
if (isReopenStandardStream(tok))
continue;
if (isOpenDevNull(tok))
continue;
// get ast parent, skip casts
const Token *parent = isNew ? tok->astParent() : tok->next()->astParent();
while (parent && parent->isCast())
parent = parent->astParent();
bool warn = true;
if (isNew) {
const Token* typeTok = tok->next();
warn = typeTok && (typeTok->isStandardType() || mSettings->library.detectContainer(typeTok));
}
if (!parent && warn) {
// Check if we are in a C++11 constructor
const Token * closingBrace = Token::findmatch(tok, "}|;");
if (closingBrace->str() == "}" && Token::Match(closingBrace->link()->tokAt(-1), "%name%") && (!isNew && precedes(tok, closingBrace->link())))
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continue;
returnValueNotUsedError(tok, tok->str());
} else if (Token::Match(parent, "%comp%|!|,|%oror%|&&|:")) {
if (parent->astParent() && parent->str() == ",")
continue;
if (parent->str() == ":") {
if (!(Token::simpleMatch(parent->astParent(), "?") && !parent->astParent()->astParent()))
continue;
}
returnValueNotUsedError(tok, tok->str());
}
}
}
//---------------------------------------------------------------------------
// Check if an exception could cause a leak in an argument constructed with
// shared_ptr/unique_ptr. For example, in the following code, it is possible
// that if g() throws an exception, the memory allocated by "new int(42)"
// could be leaked. See stackoverflow.com/questions/19034538/
// why-is-there-memory-leak-while-using-shared-ptr-as-a-function-parameter
//
// void x() {
// f(shared_ptr<int>(new int(42)), g());
// }
//---------------------------------------------------------------------------
void CheckMemoryLeakNoVar::checkForUnsafeArgAlloc(const Scope *scope)
{
// This test only applies to C++ source
if (!mTokenizer->isCPP() || !mSettings->certainty.isEnabled(Certainty::inconclusive) || !mSettings->severity.isEnabled(Severity::warning))
return;
for (const Token *tok = scope->bodyStart; tok != scope->bodyEnd; tok = tok->next()) {
if (Token::Match(tok, "%name% (")) {
const Token *endParamToken = tok->next()->link();
const Token* pointerType = nullptr;
const Token* functionCalled = nullptr;
// Scan through the arguments to the function call
for (const Token *tok2 = tok->tokAt(2); tok2 && tok2 != endParamToken; tok2 = tok2->nextArgument()) {
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const Function *func = tok2->function();
const bool isNothrow = func && (func->isAttributeNothrow() || func->isThrow());
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if (Token::Match(tok2, "shared_ptr|unique_ptr <") && Token::Match(tok2->next()->link(), "> ( new %name%")) {
pointerType = tok2;
} else if (!isNothrow) {
if (Token::Match(tok2, "%name% ("))
functionCalled = tok2;
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else if (tok2->isName() && Token::simpleMatch(tok2->next()->link(), "> ("))
functionCalled = tok2;
}
}
if (pointerType && functionCalled) {
std::string functionName = functionCalled->str();
if (functionCalled->strAt(1) == "<") {
functionName += '<';
for (const Token* tok2 = functionCalled->tokAt(2); tok2 != functionCalled->next()->link(); tok2 = tok2->next())
functionName += tok2->str();
functionName += '>';
}
std::string objectTypeName;
for (const Token* tok2 = pointerType->tokAt(2); tok2 != pointerType->next()->link(); tok2 = tok2->next())
objectTypeName += tok2->str();
unsafeArgAllocError(tok, functionName, pointerType->str(), objectTypeName);
}
}
}
}
void CheckMemoryLeakNoVar::functionCallLeak(const Token *loc, const std::string &alloc, const std::string &functionCall)
{
reportError(loc, Severity::error, "leakNoVarFunctionCall", "Allocation with " + alloc + ", " + functionCall + " doesn't release it.", CWE772, Certainty::normal);
}
void CheckMemoryLeakNoVar::returnValueNotUsedError(const Token *tok, const std::string &alloc)
{
reportError(tok, Severity::error, "leakReturnValNotUsed", "$symbol:" + alloc + "\nReturn value of allocation function '$symbol' is not stored.", CWE771, Certainty::normal);
}
void CheckMemoryLeakNoVar::unsafeArgAllocError(const Token *tok, const std::string &funcName, const std::string &ptrType, const std::string& objType)
{
const std::string factoryFunc = ptrType == "shared_ptr" ? "make_shared" : "make_unique";
reportError(tok, Severity::warning, "leakUnsafeArgAlloc",
"$symbol:" + funcName + "\n"
"Unsafe allocation. If $symbol() throws, memory could be leaked. Use " + factoryFunc + "<" + objType + ">() instead.",
CWE401,
Certainty::inconclusive); // Inconclusive because funcName may never throw
}