/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2021 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 .
*/
#include "checkmemoryleak.h"
#include "astutils.h"
#include "errorlogger.h"
#include "library.h"
#include "settings.h"
#include "symboldatabase.h"
#include "token.h"
#include "tokenize.h"
#include "utils.h"
#include
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckMemoryLeakInFunction instance1;
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
/** List of functions that can be ignored when searching for memory leaks.
* These functions don't take the address of the given pointer
* This list contains function names with const parameters e.g.: atof(const char *)
* TODO: This list should be replaced by in .cfg files.
*/
static const std::unordered_set call_func_white_list = {
"_open", "_wopen", "access", "adjtime", "asctime_r", "asprintf", "chdir", "chmod", "chown"
, "creat", "ctime_r", "execl", "execle", "execlp", "execv", "execve", "fchmod", "fcntl"
, "fdatasync", "fclose", "flock", "fmemopen", "fnmatch", "fopen", "fopencookie", "for", "free"
, "freopen", "fseeko", "fstat", "fsync", "ftello", "ftruncate", "getgrnam", "gethostbyaddr", "gethostbyname"
, "getnetbyname", "getopt", "getopt_long", "getprotobyname", "getpwnam", "getservbyname", "getservbyport"
, "glob", "gmtime", "gmtime_r", "if", "index", "inet_addr", "inet_aton", "inet_network", "initgroups"
, "ioctl", "link", "localtime_r", "lockf", "lseek", "lstat", "mkdir", "mkfifo", "mknod", "mkstemp"
, "obstack_printf", "obstack_vprintf", "open", "opendir", "parse_printf_format", "pathconf"
, "perror", "popen", "posix_fadvise", "posix_fallocate", "pread", "psignal", "pwrite", "read", "readahead"
, "readdir", "readdir_r", "readlink", "readv", "realloc", "regcomp", "return", "rewinddir", "rindex"
, "rmdir", "scandir", "seekdir", "setbuffer", "sethostname", "setlinebuf", "sizeof", "strdup"
, "stat", "stpcpy", "strcasecmp", "stricmp", "strncasecmp", "switch"
, "symlink", "sync_file_range", "telldir", "tempnam", "time", "typeid", "unlink"
, "utime", "utimes", "vasprintf", "while", "wordexp", "write", "writev"
};
//---------------------------------------------------------------------------
CheckMemoryLeak::AllocType CheckMemoryLeak::getAllocationType(const Token *tok2, nonneg int varid, std::list *callstack) const
{
// What we may have...
// * var = (char *)malloc(10);
// * var = new char[10];
// * var = strdup("hello");
// * var = strndup("hello", 3);
if (tok2 && tok2->str() == "(") {
tok2 = tok2->link();
tok2 = tok2 ? tok2->next() : nullptr;
}
if (! tok2)
return No;
if (tok2->str() == "::")
tok2 = tok2->next();
if (! tok2->isName())
return No;
if (!Token::Match(tok2, "%name% ::|. %type%")) {
// Using realloc..
AllocType reallocType = getReallocationType(tok2, varid);
if (reallocType != No)
return reallocType;
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);
if (typeTok->type() && typeTok->type()->isClassType()) {
const Scope *classScope = typeTok->type()->classScope;
if (classScope && classScope->numConstructors > 0)
return No;
}
return New;
}
if (mSettings_->posix()) {
if (Token::Match(tok2, "open|openat|creat|mkstemp|mkostemp|socket (")) {
// simple sanity check of function parameters..
// TODO: Make such check for all these functions
const int num = numberOfArguments(tok2);
if (tok2->str() == "open" && num != 2 && num != 3)
return No;
// is there a user function with this name?
if (tok2->function())
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) {
if (alloctype == mSettings_->library.deallocId("free"))
return Malloc;
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();
if (func == nullptr)
return No;
// Prevent recursion
if (callstack && std::find(callstack->begin(), callstack->end(), func) != callstack->end())
return No;
std::list 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(..;
if (tok2 && tok2->str() == "(") {
tok2 = tok2->link();
tok2 = tok2 ? tok2->next() : nullptr;
}
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 Token* arg = getArguments(tok2).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;
}
CheckMemoryLeak::AllocType CheckMemoryLeak::getDeallocationType(const Token *tok, nonneg int varid) const
{
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;
}
}
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_->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) {
if (dealloctype == mSettings_->library.deallocId("free"))
return Malloc;
if (dealloctype == mSettings_->library.deallocId("fclose"))
return File;
return Library::ismemory(dealloctype) ? OtherMem : OtherRes;
}
}
argNr++;
}
}
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;
}
//--------------------------------------------------------------------------
//--------------------------------------------------------------------------
void CheckMemoryLeak::memoryLeak(const Token *tok, const std::string &varname, AllocType alloctype) const
{
if (alloctype == CheckMemoryLeak::File ||
alloctype == CheckMemoryLeak::Pipe ||
alloctype == CheckMemoryLeak::Fd ||
alloctype == CheckMemoryLeak::OtherRes)
resourceLeakError(tok, varname);
else
memleakError(tok, varname);
}
//---------------------------------------------------------------------------
void CheckMemoryLeak::reportErr(const Token *tok, Severity::SeverityType severity, const std::string &id, const std::string &msg, const CWE &cwe) const
{
std::list callstack;
if (tok)
callstack.push_back(tok);
reportErr(callstack, severity, id, msg, cwe);
}
void CheckMemoryLeak::reportErr(const std::list &callstack, Severity::SeverityType 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, mSettings_->bugHunting);
if (mErrorLogger_)
mErrorLogger_->reportErr(errmsg);
else
Check::reportError(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 + ": $symbol";
reportErr(tok, Severity::error, "resourceLeak", errmsg, CWE(775U));
}
void CheckMemoryLeak::deallocDeallocError(const Token *tok, const std::string &varname) const
{
reportErr(tok, Severity::error, "deallocDealloc", "$symbol:" + varname + "\nDeallocating a deallocated pointer: $symbol", CWE(415U));
}
void CheckMemoryLeak::deallocuseError(const Token *tok, const std::string &varname) const
{
reportErr(tok, Severity::error, "deallocuse", "$symbol:" + varname + "\nDereferencing '$symbol' after it is deallocated / released", CWE(416U));
}
void CheckMemoryLeak::mismatchSizeError(const Token *tok, const std::string &sz) const
{
reportErr(tok, Severity::error, "mismatchSize", "The allocated size " + sz + " is not a multiple of the underlying type's size.", CWE(131U));
}
void CheckMemoryLeak::mismatchAllocDealloc(const std::list &callstack, const std::string &varname) const
{
reportErr(callstack, Severity::error, "mismatchAllocDealloc", "$symbol:" + varname + "\nMismatching allocation and deallocation: $symbol", CWE(762U));
}
CheckMemoryLeak::AllocType CheckMemoryLeak::functionReturnType(const Function* func, std::list *callstack) const
{
if (!func || !func->hasBody() || !func->functionScope)
return No;
// Get return pointer..
int varid = 0;
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") {
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)
varid = tok->varId();
break;
}
}
// Not returning pointer value..
if (varid == 0)
return No;
// 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?
const Variable *var = mTokenizer_->getSymbolDatabase()->getVariableFromVarId(varid);
if (!var || !var->isLocal() || var->isStatic())
return No;
// Check if return pointer is allocated..
AllocType allocType = No;
for (const Token* tok = func->functionScope->bodyStart; tok != func->functionScope->bodyEnd; tok = tok->next()) {
if (Token::Match(tok, "%varid% =", varid)) {
allocType = getAllocationType(tok->tokAt(2), varid, callstack);
}
if (Token::Match(tok, "= %varid% ;", varid)) {
return No;
}
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;
}
const char *CheckMemoryLeak::functionArgAlloc(const Function *func, nonneg int targetpar, AllocType &allocType) const
{
allocType = No;
if (!func || !func->functionScope)
return "";
if (!Token::simpleMatch(func->retDef, "void"))
return "";
std::list::const_iterator arg = func->argumentList.begin();
for (; arg != func->argumentList.end(); ++arg) {
if (arg->index() == targetpar-1)
break;
}
if (arg == func->argumentList.end())
return "";
// Is **
if (!arg->isPointer())
return "";
const Token* tok = arg->typeEndToken();
tok = tok->previous();
if (tok->str() != "*")
return "";
// Check if pointer is allocated.
bool realloc = false;
for (tok = func->functionScope->bodyStart; tok && tok != func->functionScope->bodyEnd; tok = tok->next()) {
if (tok->varId() == arg->declarationId()) {
if (Token::Match(tok->tokAt(-3), "free ( * %name% )")) {
realloc = true;
allocType = No;
} else if (Token::Match(tok->previous(), "* %name% =")) {
allocType = getAllocationType(tok->tokAt(2), arg->declarationId());
if (allocType != No) {
if (realloc)
return "realloc";
return "alloc";
}
} else {
// unhandled variable usage: bailout
return "";
}
}
}
return "";
}
static bool notvar(const Token *tok, nonneg int varid)
{
if (!tok)
return false;
if (Token::Match(tok, "&&|;"))
return notvar(tok->astOperand1(),varid) || notvar(tok->astOperand2(),varid);
if (tok->str() == "(" && Token::Match(tok->astOperand1(), "UNLIKELY|LIKELY"))
return notvar(tok->astOperand2(), varid);
const Token *vartok = astIsVariableComparison(tok, "==", "0");
return vartok && (vartok->varId() == varid);
}
static bool ifvar(const Token *tok, nonneg int varid, const std::string &comp, const std::string &rhs)
{
if (!Token::simpleMatch(tok, "if ("))
return false;
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;
const Token *vartok = astIsVariableComparison(condition, comp, rhs);
return (vartok && vartok->varId() == varid);
}
bool CheckMemoryLeakInFunction::test_white_list(const std::string &funcname, const Settings *settings, bool cpp)
{
return ((call_func_white_list.find(funcname)!=call_func_white_list.end()) || settings->library.isLeakIgnore(funcname) || (cpp && funcname == "delete"));
}
//---------------------------------------------------------------------------
// 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:
// a = malloc(10); a = realloc(a, 100);
//---------------------------------------------------------------------------
static bool isNoArgument(const SymbolDatabase* symbolDatabase, nonneg int varid)
{
const Variable* var = symbolDatabase->getVariableFromVarId(varid);
return var && !var->isArgument();
}
void CheckMemoryLeakInFunction::checkReallocUsage()
{
// only check functions
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();
}
if (!arg || !tok2)
continue;
if (!((tok->varId() == arg->varId()) && isNoArgument(symbolDatabase, tok->varId())))
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()))
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);
// Check that the allocation isn't followed immediately by an 'if (!var) { error(); }' that might handle failure
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))
continue;
}
memleakUponReallocFailureError(tok, reallocTok->str(), tok->str());
}
}
}
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// Checks for memory leaks in classes..
//---------------------------------------------------------------------------
void CheckMemoryLeakInClass::check()
{
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
// only check classes and structures
for (const Scope * scope : symbolDatabase->classAndStructScopes) {
for (const Variable &var : scope->varlist) {
if (!var.isStatic() && var.isPointer()) {
// allocation but no deallocation of private variables in public function..
const Token *tok = var.typeStartToken();
// Either it is of standard type or a non-derived type
if (tok->isStandardType() || (var.type() && var.type()->derivedFrom.empty())) {
if (var.isPrivate())
checkPublicFunctions(scope, var.nameToken());
variable(scope, var.nameToken());
}
}
}
}
}
void CheckMemoryLeakInClass::variable(const Scope *scope, const Token *tokVarname)
{
const std::string& varname = tokVarname->str();
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
for (const Function &func : scope->functionList) {
const bool constructor = func.isConstructor();
const bool destructor = func.isDestructor();
if (!func.hasBody()) {
if (destructor) { // implementation for destructor is not seen => assume it deallocates all variables properly
deallocInDestructor = true;
memberDealloc = CheckMemoryLeak::Many;
}
continue;
}
bool body = false;
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;
AllocType alloc = getAllocationType(tok->tokAt(body ? 2 : 3), 0);
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) {
std::list callstack;
callstack.push_back(tok);
mismatchAllocDealloc(callstack, 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;
if (dealloc != CheckMemoryLeak::No) {
if (destructor)
deallocInDestructor = true;
// several types of allocation/deallocation?
if (memberDealloc != CheckMemoryLeak::No && memberDealloc != dealloc)
dealloc = CheckMemoryLeak::Many;
if (dealloc != CheckMemoryLeak::Many && memberAlloc != CheckMemoryLeak::No && memberAlloc != Many && memberAlloc != dealloc) {
std::list callstack;
callstack.push_back(tok);
mismatchAllocDealloc(callstack, classname + "::" + varname);
}
memberDealloc = dealloc;
}
// Function call .. possible deallocation
else if (Token::Match(tok->previous(), "[{};] %name% (")) {
if (!CheckMemoryLeakInFunction::test_white_list(tok->str(), mSettings, mTokenizer->isCPP())) {
return;
}
}
}
}
}
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"
"$symbol:" + varname + "\n"
"Class '" + classname + "' is unsafe, '" + varname + "' can leak by wrong usage.\n"
"The class '" + classname + "' is unsafe, wrong usage can cause memory/resource leaks for '" + varname + "'. This can for instance be fixed by adding proper cleanup in the destructor.", CWE398, Certainty::normal);
}
void CheckMemoryLeakInClass::checkPublicFunctions(const Scope *scope, const Token *classtok)
{
// Check that public functions deallocate the pointers that they allocate.
// There is no checking how these functions are used and therefore it
// isn't established if there is real leaks or not.
if (!mSettings->severity.isEnabled(Severity::warning))
return;
const int varid = classtok->varId();
// Parse public functions..
// If they allocate member variables, they should also deallocate
for (const Function &func : scope->functionList) {
if ((func.type == Function::eFunction || func.type == Function::eOperatorEqual) &&
func.access == AccessControl::Public && func.hasBody()) {
const Token *tok2 = func.functionScope->bodyStart->next();
if (Token::Match(tok2, "%varid% =", varid)) {
const CheckMemoryLeak::AllocType alloc = getAllocationType(tok2->tokAt(2), varid);
if (alloc != CheckMemoryLeak::No)
publicAllocationError(tok2, tok2->str());
} else if (Token::Match(tok2, "%type% :: %varid% =", varid) &&
tok2->str() == scope->className) {
const CheckMemoryLeak::AllocType alloc = getAllocationType(tok2->tokAt(4), varid);
if (alloc != CheckMemoryLeak::No)
publicAllocationError(tok2, tok2->strAt(2));
}
}
}
}
void CheckMemoryLeakInClass::publicAllocationError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::warning, "publicAllocationError", "$symbol:" + varname + "\nPossible leak in public function. The pointer '$symbol' is not deallocated before it is allocated.", CWE398, Certainty::normal);
}
void CheckMemoryLeakStructMember::check()
{
const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Variable* var : symbolDatabase->variableList()) {
if (!var || !var->isLocal() || var->isStatic() || var->isReference())
continue;
if (var->typeEndToken()->isStandardType())
continue;
if (var->scope()->hasInlineOrLambdaFunction())
continue;
checkStructVariable(var);
}
}
bool CheckMemoryLeakStructMember::isMalloc(const Variable *variable)
{
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;
} else if (Token::Match(tok2, "%varid% = malloc|kmalloc (", declarationId)) {
alloc = true;
}
}
return alloc;
}
void CheckMemoryLeakStructMember::checkStructVariable(const Variable * const variable)
{
// Is struct variable a pointer?
if (variable->isPointer()) {
// Check that variable is allocated with malloc
if (!isMalloc(variable))
return;
} else if (!mTokenizer->isC() && (!variable->typeScope() || variable->typeScope()->getDestructor())) {
// For non-C code a destructor might cleanup members
return;
}
// Check struct..
int indentlevel2 = 0;
for (const Token *tok2 = variable->nameToken(); tok2 && tok2 != variable->scope()->bodyEnd; tok2 = tok2->next()) {
if (tok2->str() == "{")
++indentlevel2;
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 (Token::Match(tok2->previous(), "[;{}] %varid% . %var% =", variable->declarationId())) {
if (getAllocationType(tok2->tokAt(4), tok2->tokAt(2)->varId()) == AllocType::No)
continue;
const int structid(variable->declarationId());
const int structmemberid(tok2->tokAt(2)->varId());
// This struct member is allocated.. check that it is deallocated
int indentlevel3 = indentlevel2;
for (const Token *tok3 = tok2; tok3; tok3 = tok3->next()) {
if (tok3->str() == "{")
++indentlevel3;
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;
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, "free|kfree ( %varid% )", structid)) {
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..
int indentlevel4 = 0;
for (const Token *tok4 = tok3; tok4; tok4 = tok4->next()) {
if (tok4->str() == "{")
++indentlevel4;
else if (tok4->str() == "}") {
--indentlevel4;
if (indentlevel4 == 0)
break;
} else if (Token::Match(tok4, "free|kfree ( %var% . %varid% )", structmemberid)) {
break;
}
}
// was there a proper deallocation?
if (indentlevel4 > 0)
break;
}
// Returning from function..
else if (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)) {
memoryLeak(tok3, variable->name() + "." + tok2->strAt(2), Malloc);
}
break;
}
// struct assignment..
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% (")) {
// Calling non-function / function that doesn't deallocate?
if (CheckMemoryLeakInFunction::test_white_list(tok3->str(), mSettings, mTokenizer->isCPP()))
continue;
// Check if the struct is used..
bool deallocated = false;
const Token* const end4 = tok3->linkAt(1);
for (const Token *tok4 = tok3; tok4 != end4; tok4 = tok4->next()) {
if (Token::Match(tok4, "[(,] &| %varid% [,)]", structid)) {
/** @todo check if the function deallocates the memory */
deallocated = true;
break;
}
if (Token::Match(tok4, "[(,] &| %varid% . %name% [,)]", structid)) {
/** @todo check if the function deallocates the memory */
deallocated = true;
break;
}
}
if (deallocated)
break;
}
}
}
}
}
void CheckMemoryLeakNoVar::check()
{
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
// only check functions
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 (!Token::Match(tok, "%name% ("))
continue;
// check if the output of the function is assigned
const Token* tok2 = tok->next()->astParent();
while (tok2 && tok2->isCast())
tok2 = tok2->astParent();
if (tok2 && tok2->isAssignmentOp())
continue;
const std::string& functionName = tok->str();
if ((mTokenizer->isCPP() && functionName == "delete") ||
functionName == "free" ||
functionName == "fclose" ||
functionName == "realloc" ||
functionName == "return")
continue;
if (!CheckMemoryLeakInFunction::test_white_list(functionName, mSettings, mTokenizer->isCPP()))
continue;
const std::vector args = getArguments(tok);
for (const Token* arg : args) {
if (arg->isOp())
continue;
while (arg->astOperand1())
arg = arg->astOperand1();
if (getAllocationType(arg, 0) == No)
continue;
if (isReopenStandardStream(arg))
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()) {
if (!Token::Match(tok, "%name% ("))
continue;
if (tok->varId())
continue;
const AllocType allocType = getAllocationType(tok, 0);
if (allocType == No)
continue;
if (tok != tok->next()->astOperand1())
continue;
if (isReopenStandardStream(tok))
continue;
// get ast parent, skip casts
const Token *parent = tok->next()->astParent();
while (parent && parent->str() == "(" && !parent->astOperand2())
parent = parent->astParent();
if (!parent) {
// 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%"))
continue;
returnValueNotUsedError(tok, tok->str());
} else if (Token::Match(parent, "%comp%|!")) {
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(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()) {
const Function *func = tok2->function();
const bool isNothrow = func && (func->isAttributeNothrow() || func->isThrow());
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;
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
}