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2176 lines (1855 loc) · 90 KB
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/*
* Cppcheck - A tool for static C/C++ code analysis
* Copyright (C) 2007-2014 Daniel Marjamäki and 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/>.
*/
//---------------------------------------------------------------------------
// Buffer overrun..
//---------------------------------------------------------------------------
#include "checkbufferoverrun.h"
#include "tokenize.h"
#include "mathlib.h"
#include "symboldatabase.h"
#include <algorithm>
#include <sstream>
#include <list>
#include <cassert> // <- assert
#include <cstdlib>
//---------------------------------------------------------------------------
// Register this check class (by creating a static instance of it)
namespace {
CheckBufferOverrun instance;
}
//---------------------------------------------------------------------------
static void makeArrayIndexOutOfBoundsError(std::ostream& oss, const CheckBufferOverrun::ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index)
{
oss << "Array '" << arrayInfo.varname();
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
oss << "[" << arrayInfo.num(i) << "]";
if (index.size() == 1)
oss << "' accessed at index " << index[0] << ", which is";
else {
oss << "' index " << arrayInfo.varname();
for (unsigned int i = 0; i < index.size(); ++i)
oss << "[" << index[i] << "]";
}
oss << " out of bounds.";
}
void CheckBufferOverrun::arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index)
{
std::ostringstream oss;
makeArrayIndexOutOfBoundsError(oss, arrayInfo, index);
reportError(tok, Severity::error, "arrayIndexOutOfBounds", oss.str());
}
void CheckBufferOverrun::arrayIndexOutOfBoundsError(const Token *tok, const ArrayInfo &arrayInfo, const std::vector<ValueFlow::Value> &index)
{
std::ostringstream errmsg;
errmsg << "Array '" << arrayInfo.varname();
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
errmsg << "[" << arrayInfo.num(i) << "]";
if (index.size() == 1)
errmsg << "' accessed at index " << index[0].intvalue << ", which is out of bounds.";
else {
errmsg << "' index " << arrayInfo.varname();
for (unsigned int i = 0; i < index.size(); ++i)
errmsg << "[" << index[i].intvalue << "]";
errmsg << " out of bounds.";
}
const Token *condition = nullptr;
for (unsigned int i = 0; i < index.size(); ++i) {
if (condition == nullptr)
condition = index[i].condition;
}
if (condition != nullptr) {
errmsg << " Otherwise condition '" << condition->expressionString() << "' is redundant.";
std::list<const Token *> callstack;
callstack.push_back(tok);
callstack.push_back(condition);
reportError(callstack, Severity::warning, "arrayIndexOutOfBoundsCond", errmsg.str());
} else {
reportError(tok, Severity::error, "arrayIndexOutOfBounds", errmsg.str());
}
}
void CheckBufferOverrun::arrayIndexOutOfBoundsError(const std::list<const Token *> &callstack, const ArrayInfo &arrayInfo, const std::vector<MathLib::bigint> &index)
{
std::ostringstream oss;
makeArrayIndexOutOfBoundsError(oss, arrayInfo, index);
reportError(callstack, Severity::error, "arrayIndexOutOfBounds", oss.str());
}
static std::string bufferOverrunMessage(std::string varnames)
{
varnames.erase(std::remove(varnames.begin(), varnames.end(), ' '), varnames.end());
std::string errmsg("Buffer is accessed out of bounds");
if (!varnames.empty())
errmsg += ": " + varnames;
else
errmsg += ".";
return errmsg;
}
void CheckBufferOverrun::bufferOverrunError(const Token *tok, const std::string &varnames)
{
reportError(tok, Severity::error, "bufferAccessOutOfBounds", bufferOverrunMessage(varnames));
}
void CheckBufferOverrun::bufferOverrunError(const std::list<const Token *> &callstack, const std::string &varnames)
{
reportError(callstack, Severity::error, "bufferAccessOutOfBounds", bufferOverrunMessage(varnames));
}
void CheckBufferOverrun::possibleBufferOverrunError(const Token *tok, const std::string &src, const std::string &dst, bool cat)
{
if (cat)
reportError(tok, Severity::warning, "possibleBufferAccessOutOfBounds",
"Possible buffer overflow if strlen(" + src + ") is larger than sizeof(" + dst + ")-strlen(" + dst +").\n"
"Possible buffer overflow if strlen(" + src + ") is larger than sizeof(" + dst + ")-strlen(" + dst +"). "
"The source buffer is larger than the destination buffer so there is the potential for overflowing the destination buffer.");
else
reportError(tok, Severity::warning, "possibleBufferAccessOutOfBounds",
"Possible buffer overflow if strlen(" + src + ") is larger than or equal to sizeof(" + dst + ").\n"
"Possible buffer overflow if strlen(" + src + ") is larger than or equal to sizeof(" + dst + "). "
"The source buffer is larger than the destination buffer so there is the potential for overflowing the destination buffer.");
}
void CheckBufferOverrun::possibleReadlinkBufferOverrunError(const Token* tok, const std::string &funcname, const std::string &varname)
{
const std::string errmsg = funcname + "() might return the full size of '" + varname + "'. Lower the supplied size by one.\n" +
funcname + "() might return the full size of '" + varname + "'. "
"If a " + varname + "[len] = '\\0'; statement follows, it will overrun the buffer. Lower the supplied size by one.";
reportError(tok, Severity::warning, "possibleReadlinkBufferOverrun", errmsg, true);
}
void CheckBufferOverrun::strncatUsageError(const Token *tok)
{
if (_settings && !_settings->isEnabled("warning"))
return;
reportError(tok, Severity::warning, "strncatUsage",
"Dangerous usage of strncat - 3rd parameter is the maximum number of characters to append.\n"
"strncat appends at max its 3rd parameter's amount of characters. The safe way to use "
"strncat is to calculate remaining space in the buffer and use it as 3rd parameter.");
}
void CheckBufferOverrun::outOfBoundsError(const Token *tok, const std::string &what, const bool show_size_info, const MathLib::bigint &supplied_size, const MathLib::bigint &actual_size)
{
std::ostringstream oss;
oss << what << " is out of bounds";
if (show_size_info)
oss << ": Supplied size " << supplied_size << " is larger than actual size " << actual_size;
oss << '.';
reportError(tok, Severity::error, "outOfBounds", oss.str());
}
void CheckBufferOverrun::pointerOutOfBoundsError(const Token *tok, const std::string &object)
{
reportError(tok, Severity::portability, "pointerOutOfBounds", "Undefined behaviour: Pointer arithmetic result does not point into or just past the end of the " + object + ".\n"
"Undefined behaviour: The result of this pointer arithmetic does not point into or just one element past the end of the " + object + ". Further information: https://www.securecoding.cert.org/confluence/display/seccode/ARR30-C.+Do+not+form+or+use+out+of+bounds+pointers+or+array+subscripts");
}
void CheckBufferOverrun::sizeArgumentAsCharError(const Token *tok)
{
if (_settings && !_settings->isEnabled("warning"))
return;
reportError(tok, Severity::warning, "sizeArgumentAsChar", "The size argument is given as a char constant.");
}
void CheckBufferOverrun::terminateStrncpyError(const Token *tok, const std::string &varname)
{
reportError(tok, Severity::warning, "terminateStrncpy",
"The buffer '" + varname + "' may not be null-terminated after the call to strncpy().\n"
"If the source string's size fits or exceeds the given size, strncpy() does not add a "
"zero at the end of the buffer. This causes bugs later in the code if the code "
"assumes buffer is null-terminated.", true);
}
void CheckBufferOverrun::cmdLineArgsError(const Token *tok)
{
reportError(tok, Severity::error, "insecureCmdLineArgs", "Buffer overrun possible for long command line arguments.");
}
void CheckBufferOverrun::bufferNotZeroTerminatedError(const Token *tok, const std::string &varname, const std::string &function)
{
const std::string errmsg = "The buffer '" + varname + "' is not null-terminated after the call to " + function + "().\n"
"The buffer '" + varname + "' is not null-terminated after the call to " + function + "(). "
"This will cause bugs later in the code if the code assumes the buffer is null-terminated.";
reportError(tok, Severity::warning, "bufferNotZeroTerminated", errmsg, true);
}
void CheckBufferOverrun::argumentSizeError(const Token *tok, const std::string &functionName, const std::string &varname)
{
reportError(tok, Severity::warning, "argumentSize", "The array '" + varname + "' is too small, the function '" + functionName + "' expects a bigger one.");
}
void CheckBufferOverrun::negativeMemoryAllocationSizeError(const Token *tok)
{
reportError(tok, Severity::error, "negativeMemoryAllocationSize",
"Memory allocation size is negative.\n"
"Memory allocation size is negative."
"Negative allocation size has no specified behaviour.");
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
// Check array usage..
//---------------------------------------------------------------------------
/**
* bailout if variable is used inside if/else/switch block or if there is "break"
* @param tok token for "if" or "switch"
* @param varid variable id
* @return is bailout recommended?
*/
static bool bailoutIfSwitch(const Token *tok, const unsigned int varid)
{
// Used later to check if the body belongs to a "if"
const bool is_if = tok->str() == "if";
const Token* end = tok->linkAt(1)->linkAt(1);
if (Token::simpleMatch(end, "} else {")) // scan the else-block
end = end->linkAt(2);
if (Token::simpleMatch(end, "{")) // Ticket #5203: Invalid code, bailout
return true;
for (; tok && tok != end; tok = tok->next()) {
// If scanning a "if" block then bailout for "break"
if (is_if && (tok->str() == "break" || tok->str() == "continue"))
return true;
// bailout for "return"
else if (tok->str() == "return")
return true;
// bailout if varid is found
else if (tok->varId() == varid)
return true;
}
// No bailout stuff found => return false
return false;
}
/**
* Parse for loop initialization statement. Look for a counter variable
* \param tok [in] first token inside the parentheses
* \param varid [out] varid of counter variable
* \param varname [out] name of counter variable
* \param init_value [out] init value of counter variable
* \return success => pointer to the for loop condition. fail => 0. If 0 is returned and varname has been set then there is
* a missing varid for the counter variable
*/
static const Token *for_init(const Token *tok, unsigned int &varid, std::string &varname, std::string &init_value)
{
if (Token::Match(tok, "%var% = %any% ;")) {
if (tok->tokAt(2)->isNumber()) {
init_value = tok->strAt(2);
}
varid = tok->varId();
varname = tok->str();
if (varid == 0)
return 0; // failed
tok = tok->tokAt(4);
} else if (Token::Match(tok, "%type% %var% = %any% ;")) {
if (tok->tokAt(3)->isNumber()) {
init_value = tok->strAt(3);
}
varid = tok->next()->varId();
varname = tok->next()->str();
tok = tok->tokAt(5);
} else if (Token::Match(tok, "%type% %type% %var% = %any% ;")) {
if (tok->tokAt(4)->isNumber()) {
init_value = tok->strAt(4);
}
varid = tok->tokAt(2)->varId();
varname = tok->strAt(2);
tok = tok->tokAt(6);
} else
return 0;
if (!init_value.empty() && (Token::Match(tok, "-- %varid%", varid) || Token::Match(tok, "%varid% --", varid))) {
init_value = MathLib::subtract(init_value, "1");
}
return tok;
}
/** Parse for condition */
static bool for_condition(const Token *tok2, unsigned int varid, std::string &min_value, std::string &max_value, bool &maxMinFlipped)
{
if (Token::Match(tok2, "%varid% < %num% ;|&&|%oror%", varid) ||
Token::Match(tok2, "%varid% != %num% ; ++ %varid%", varid) ||
Token::Match(tok2, "%varid% != %num% ; %varid% ++", varid)) {
maxMinFlipped = false;
const MathLib::bigint value = MathLib::toLongNumber(tok2->strAt(2));
max_value = MathLib::toString(value - 1);
} else if (Token::Match(tok2, "%varid% <= %num% ;|&&|%oror%", varid)) {
maxMinFlipped = false;
max_value = tok2->strAt(2);
} else if (Token::Match(tok2, "%num% < %varid% ;|&&|%oror%", varid) ||
Token::Match(tok2, "%num% != %varid% ; ++ %varid%", varid) ||
Token::Match(tok2, "%num% != %varid% ; %varid% ++", varid)) {
maxMinFlipped = true;
const MathLib::bigint value = MathLib::toLongNumber(tok2->str());
max_value = min_value;
min_value = MathLib::toString(value + 1);
} else if (Token::Match(tok2, "%num% <= %varid% ;|&&|%oror%", varid)) {
maxMinFlipped = true;
max_value = min_value;
min_value = tok2->str();
} else if (Token::Match(tok2, "%varid% -- ; )", varid) ||
Token::Match(tok2, "-- %varid% ; )", varid)) {
maxMinFlipped = true;
max_value = min_value;
min_value = (tok2->str() == "--") ? "1" : "0";
} else {
// parse condition
while (tok2 && tok2->str() != ";") {
if (tok2->str() == "(")
tok2 = tok2->link();
else if (tok2->str() == ")") // unexpected ")" => break
break;
if (tok2->str() == "&&" || tok2->str() == "||") {
if (for_condition(tok2->next(), varid, min_value, max_value, maxMinFlipped))
return true;
}
tok2 = tok2->next();
}
return false;
}
return true;
}
/**
* calculate maximum value of loop variable
* @param stepvalue token that contains the step value
* @param min_value the minimum value of loop variable
* @param max_value maximum value of the loop variable
*/
static bool for_maxvalue(const Token * const stepvalue, const std::string &min_value, std::string &max_value)
{
if (!MathLib::isInt(stepvalue->str()))
return false;
// We have for example code: "for(i=2;i<22;i+=6)
// We can calculate that max value for i is 20, not 21
// 21-2 = 19
// 19/6 = 3
// 6*3+2 = 20
const MathLib::bigint num = MathLib::toLongNumber(stepvalue->str());
MathLib::bigint max = MathLib::toLongNumber(max_value);
const MathLib::bigint min = MathLib::toLongNumber(min_value);
max = ((max - min) / num) * num + min;
max_value = MathLib::toString(max);
return true;
}
/**
* Parse the third sub-statement in for head
* \param tok first token
* \param varid variable id of counter
* \param min_value min value of counter
* \param max_value max value of counter
* \param maxMinFlipped counting from max to min
*/
static bool for3(const Token * const tok,
unsigned int varid,
std::string &min_value,
std::string &max_value,
const bool maxMinFlipped)
{
assert(tok != nullptr);
if (Token::Match(tok, "%varid% = %num% + %varid% )", varid)) {
if (!for_maxvalue(tok->tokAt(2), min_value, max_value))
return false;
} else if (Token::Match(tok, "%varid% = %varid% + %num% )", varid)) {
if (!for_maxvalue(tok->tokAt(4), min_value, max_value))
return false;
} else if (Token::Match(tok, "%varid% = %num% - %varid% )", varid)) {
if (!for_maxvalue(tok->tokAt(2), min_value, max_value))
return false;
} else if (Token::Match(tok, "%varid% = %varid% - %num% )", varid)) {
if (!for_maxvalue(tok->tokAt(4), min_value, max_value))
return false;
} else if (Token::Match(tok, "--| %varid% --| )", varid)) {
if (!maxMinFlipped && MathLib::toLongNumber(min_value) < MathLib::toLongNumber(max_value)) {
// Code relies on the fact that integer will overflow:
// for (unsigned int i = 3; i < 5; --i)
// Set min value in this case to zero.
max_value = min_value;
min_value = "0";
}
} else if (! Token::Match(tok, "++| %varid% ++| )", varid)) {
return false;
}
return true;
}
/**
* Check is the counter variable increased elsewhere inside the loop or used
* for anything else except reading
* \param tok1 first token of for-body
* \param varid counter variable id
* \return bailout needed => true
*/
static bool for_bailout(const Token * const tok1, unsigned int varid)
{
for (const Token *loopTok = tok1; loopTok && loopTok != tok1->link(); loopTok = loopTok->next()) {
if (loopTok->varId() == varid) {
// Counter variable used inside loop
if (Token::Match(loopTok->next(), "++|--|=") ||
(loopTok->previous()->type() == Token::eIncDecOp)) {
return true;
}
}
}
return false;
}
void CheckBufferOverrun::parse_for_body(const Token *tok, const ArrayInfo &arrayInfo, const std::string &strindex, bool condition_out_of_bounds, unsigned int counter_varid, const std::string &min_counter_value, const std::string &max_counter_value)
{
unsigned int arrayInfoDeclarationId = arrayInfo.declarationId();
const std::string pattern = (arrayInfoDeclarationId ? std::string("%varid%") : arrayInfo.varname()) + " [ " + strindex + " ]";
for (const Token* tok2 = tok; tok2 && tok2 != tok->link(); tok2 = tok2->next()) {
// TestBufferOverrun::array_index_for_question
if (tok2->str() == "?") {
// does condition check counter variable?
bool usesCounter = false;
const Token *tok3 = tok2->previous();
while (Token::Match(tok3, "%comp%|%num%|%var%|)")) {
if (tok3->str() == strindex) {
usesCounter = true;
break;
}
tok3 = tok3->previous();
}
// If strindex is used in the condition then skip the
// conditional expressions
if (usesCounter) {
while (tok2 && !Token::Match(tok2, "[)],;]")) {
if (tok2->str() == "(" || tok2->str() == "[")
tok2 = tok2->link();
tok2 = tok2->next();
}
if (!tok2)
break;
continue;
}
}
if (Token::simpleMatch(tok2, "for (") && Token::simpleMatch(tok2->next()->link(), ") {")) {
const Token *endpar = tok2->next()->link();
const Token *startbody = endpar->next();
const Token *endbody = startbody->link();
tok2 = endbody;
continue;
}
if (Token::Match(tok2, "if|switch")) {
if (bailoutIfSwitch(tok2, arrayInfoDeclarationId))
break;
}
if (condition_out_of_bounds && Token::Match(tok2, pattern.c_str(), arrayInfoDeclarationId)) {
bufferOverrunError(tok2, arrayInfo.varname());
break;
}
else if (arrayInfoDeclarationId && tok2->varId() && counter_varid > 0 && !min_counter_value.empty() && !max_counter_value.empty()) {
// Is the loop variable used to calculate the array index?
// In this scope it is determined if such calculated
// array indexes are out of bounds.
// Only the minimum and maximum results of the calculation is
// determined
// Minimum calculated array index
int min_index = 0;
// Maximum calculated array index
int max_index = 0;
if (Token::Match(tok2, "%varid% [ %var% +|-|*|/ %num% ]", arrayInfoDeclarationId) &&
tok2->tokAt(2)->varId() == counter_varid) {
// operator: +-*/
const char action = tok2->strAt(3)[0];
// second operator
const std::string &second(tok2->strAt(4));
//printf("min_index: %s %c %s\n", min_counter_value.c_str(), action, second.c_str());
//printf("max_index: %s %c %s\n", max_counter_value.c_str(), action, second.c_str());
min_index = std::atoi(MathLib::calculate(min_counter_value, second, action).c_str());
max_index = std::atoi(MathLib::calculate(max_counter_value, second, action).c_str());
} else if (Token::Match(tok2, "%varid% [ %num% +|-|*|/ %var% ]", arrayInfoDeclarationId) &&
tok2->tokAt(4)->varId() == counter_varid) {
// operator: +-*/
const char action = tok2->strAt(3)[0];
// first operand
const std::string &first(tok2->strAt(2));
//printf("min_index: %s %c %s\n", first.c_str(), action, min_counter_value.c_str());
//printf("max_index: %s %c %s\n", first.c_str(), action, max_counter_value.c_str());
min_index = std::atoi(MathLib::calculate(first, min_counter_value, action).c_str());
max_index = std::atoi(MathLib::calculate(first, max_counter_value, action).c_str());
}
else {
continue;
}
//printf("min_index = %d, max_index = %d, size = %d\n", min_index, max_index, size);
if (min_index < 0 || max_index < 0) {
std::vector<MathLib::bigint> indexes;
indexes.push_back(std::min(min_index, max_index));
arrayIndexOutOfBoundsError(tok2, arrayInfo, indexes);
}
// skip 0 length arrays
if (arrayInfo.num(0) == 0)
;
// taking address.
else if (tok2->previous()->str() == "&" && max_index == arrayInfo.num(0))
;
else if (arrayInfo.num(0) && (min_index >= arrayInfo.num(0) || max_index >= arrayInfo.num(0))) {
std::vector<MathLib::bigint> indexes;
indexes.push_back(std::max(min_index, max_index));
arrayIndexOutOfBoundsError(tok2, arrayInfo, indexes);
}
}
}
}
void CheckBufferOverrun::checkFunctionParameter(const Token &tok, unsigned int par, const ArrayInfo &arrayInfo, std::list<const Token *> callstack)
{
// total_size : which parameter in function call takes the total size?
std::map<std::string, unsigned int> total_size;
if (!(Token::simpleMatch(tok.previous(), ".") || Token::Match(tok.tokAt(-2), "!!std ::"))) {
total_size["fgets"] = 2; // The second argument for fgets can't exceed the total size of the array
total_size["memcmp"] = 3;
total_size["memcpy"] = 3;
total_size["memmove"] = 3;
total_size["memchr"] = 3;
if (par == 1) {
// reading from array
// if it is zero terminated properly there won't be buffer overruns
total_size["strncat"] = 3;
total_size["strncpy"] = 3;
total_size["memset"] = 3;
total_size["fread"] = 1001; // parameter 2 * parameter 3
total_size["fwrite"] = 1001; // parameter 2 * parameter 3
}
else if (par == 2) {
if (_settings->standards.posix) {
total_size["read"] = 3;
total_size["pread"] = 3;
total_size["write"] = 3;
total_size["recv"] = 3;
total_size["recvfrom"] = 3;
total_size["send"] = 3;
total_size["sendto"] = 3;
}
}
}
std::map<std::string, unsigned int>::const_iterator it = total_size.find(tok.str());
if (it != total_size.end()) {
if (arrayInfo.element_size() == 0)
return;
// arg : the index of the "wanted" argument in the function call.
const unsigned int arg = it->second;
// Parse function call. When a ',' is seen, arg is decremented.
// if arg becomes 1 then the current function parameter is the wanted parameter.
// if arg becomes 1001 then multiply current and next argument.
const Token *tok2 = tok.tokAt(2)->nextArgument();
if (arg == 3)
tok2 = tok2->nextArgument();
if ((arg == 2 || arg == 3) && tok2) {
if (Token::Match(tok2, "%num% ,|)")) {
const MathLib::bigint sz = MathLib::toLongNumber(tok2->str());
MathLib::bigint elements = 1;
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
elements *= arrayInfo.num(i);
if (sz < 0 || sz > int(elements * arrayInfo.element_size())) {
bufferOverrunError(callstack, arrayInfo.varname());
}
}
else if (Token::Match(tok2->next(), ",|)") && tok2->type() == Token::eChar) {
sizeArgumentAsCharError(tok2);
}
} else if (arg == 1001) { // special code. This parameter multiplied with the next must not exceed total_size
if (Token::Match(tok2, "%num% , %num% ,|)")) {
const MathLib::bigint sz = MathLib::toLongNumber(MathLib::multiply(tok2->str(), tok2->strAt(2)));
MathLib::bigint elements = 1;
for (unsigned int i = 0; i < arrayInfo.num().size(); ++i)
elements *= arrayInfo.num(i);
if (sz < 0 || sz > int(elements * arrayInfo.element_size())) {
bufferOverrunError(&tok, arrayInfo.varname());
}
}
}
}
// Calling a user function?
// only 1-dimensional arrays can be checked currently
else if (arrayInfo.num().size() == 1) {
const Function* const func = tok.function();
if (func && func->hasBody) {
// Get corresponding parameter..
const Variable* const parameter = func->getArgumentVar(par-1);
// Ensure that it has a compatible size..
if (!parameter || _tokenizer->sizeOfType(parameter->typeStartToken()) != arrayInfo.element_size())
return;
// No variable id occur for instance when:
// - Variable function arguments: "void f(...)"
// - Unnamed parameter: "void f(char *)"
if (parameter->declarationId() == 0)
return;
// Check the parameter usage in the function scope..
for (const Token* ftok = func->functionScope->classStart; ftok != func->functionScope->classEnd; ftok = ftok->next()) {
if (Token::Match(ftok, "if|for|switch|while (")) {
// bailout if there is buffer usage..
if (bailoutIfSwitch(ftok, parameter->declarationId())) {
break;
}
// no bailout is needed. skip the if-block
else {
// goto end of if block..
ftok = ftok->next()->link()->next()->link();
if (Token::simpleMatch(ftok, "} else {"))
ftok = ftok->linkAt(2);
if (!ftok)
break;
continue;
}
}
if (ftok->str() == "}")
break;
if (ftok->varId() == parameter->declarationId()) {
if (Token::Match(ftok->previous(), "-- %var%") ||
Token::Match(ftok, "%var% --"))
break;
if (Token::Match(ftok->previous(), ";|{|}|%op% %var% [ %num% ]")) {
const MathLib::bigint index = MathLib::toLongNumber(ftok->strAt(2));
if (index >= 0 && arrayInfo.num(0) > 0 && index >= arrayInfo.num(0)) {
std::list<const Token *> callstack2(callstack);
callstack2.push_back(ftok);
std::vector<MathLib::bigint> indexes;
indexes.push_back(index);
arrayIndexOutOfBoundsError(callstack2, arrayInfo, indexes);
}
}
}
// Calling function..
if (Token::Match(ftok, "%var% (")) {
ArrayInfo ai(arrayInfo);
ai.declarationId(parameter->declarationId());
checkFunctionCall(ftok, ai, callstack);
}
}
}
}
// Check 'float x[10]' arguments in declaration
if (_settings->isEnabled("warning")) {
const Function* const func = tok.function();
// If argument is '%type% a[num]' then check bounds against num
if (func) {
const Variable* const argument = func->getArgumentVar(par-1);
const Token *nameToken;
if (argument && Token::Match(argument->typeStartToken(), "%type% %var% [ %num% ] [,)[]")
&& (nameToken = argument->nameToken()) != nullptr) {
const Token *tok2 = nameToken->next();
MathLib::bigint argsize = _tokenizer->sizeOfType(argument->typeStartToken());
if (argsize == 100) // unknown size
argsize = 0;
while (Token::Match(tok2, "[ %num% ] [,)[]")) {
argsize *= MathLib::toLongNumber(tok2->strAt(1));
tok2 = tok2->tokAt(3);
}
MathLib::bigint arraysize = arrayInfo.element_size();
if (arraysize == 100) // unknown size
arraysize = 0;
for (unsigned int i = 0; i < arrayInfo.num().size(); i++)
arraysize *= arrayInfo.num(i);
if (Token::Match(tok2, "[,)]") && arraysize > 0 && argsize > arraysize)
argumentSizeError(&tok, tok.str(), arrayInfo.varname());
}
}
}
}
void CheckBufferOverrun::checkFunctionCall(const Token *tok, const ArrayInfo &arrayInfo, std::list<const Token *> callstack)
{
// Don't go deeper than 2 levels, the checking can get very slow
// when there is no limit
if (callstack.size() >= 2)
return;
// Prevent recursion
for (std::list<const Token*>::const_iterator it = callstack.begin(); it != callstack.end(); ++it) {
// Same function name => bail out
if (tok->str() == (*it)->str())
return;
}
callstack.push_back(tok);
const unsigned int declarationId = arrayInfo.declarationId();
const Token *tok2 = tok->tokAt(2);
// 1st parameter..
if (Token::Match(tok2, "%varid% ,|)", declarationId))
checkFunctionParameter(*tok, 1, arrayInfo, callstack);
else if (Token::Match(tok2, "%varid% + %num% ,|)", declarationId)) {
const ArrayInfo ai(arrayInfo.limit(MathLib::toLongNumber(tok2->strAt(2))));
checkFunctionParameter(*tok, 1, ai, callstack);
}
// goto 2nd parameter and check it..
tok2 = tok2->nextArgument();
if (Token::Match(tok2, "%varid% ,|)", declarationId))
checkFunctionParameter(*tok, 2, arrayInfo, callstack);
else if (Token::Match(tok2, "%varid% + %num% ,|)", declarationId)) {
const ArrayInfo ai(arrayInfo.limit(MathLib::toLongNumber(tok2->strAt(2))));
checkFunctionParameter(*tok, 2, ai, callstack);
}
}
void CheckBufferOverrun::checkScopeForBody(const Token *tok, const ArrayInfo &arrayInfo, bool &bailout)
{
bailout = false;
// Check if there is a break in the body..
{
const Token *bodyStart = tok->next()->link()->next();
const Token *bodyEnd = bodyStart->link();
if (Token::findsimplematch(bodyStart, "break ;", bodyEnd))
return;
}
const Token *tok2 = tok->tokAt(2);
const MathLib::bigint size = arrayInfo.num(0);
std::string counter_name;
unsigned int counter_varid = 0;
std::string counter_init_value;
tok2 = for_init(tok2, counter_varid, counter_name, counter_init_value);
if (tok2 == 0 && !counter_name.empty())
_tokenizer->getSymbolDatabase()->debugMessage(tok, "for loop variable \'" + counter_name + "\' has varid 0.");
if (tok2 == 0 || counter_varid == 0)
return;
bool maxMinFlipped = false;
std::string min_counter_value = counter_init_value;
std::string max_counter_value;
if (!for_condition(tok2, counter_varid, min_counter_value, max_counter_value, maxMinFlipped)) {
// Can't understand the condition. Check that the start value
// is used correctly
const Token * const startForScope = tok->next()->link()->next();
if (!for_bailout(startForScope, counter_varid)) {
// Get index variable and stopsize.
bool condition_out_of_bounds = bool(size > 0);
if (MathLib::toLongNumber(counter_init_value) < size)
condition_out_of_bounds = false;
parse_for_body(startForScope, arrayInfo, counter_name, condition_out_of_bounds, counter_varid, counter_init_value, counter_init_value);
}
return;
}
// Get index variable and stopsize.
bool condition_out_of_bounds = bool(size > 0);
if (MathLib::toLongNumber(max_counter_value) < size)
condition_out_of_bounds = false;
// Goto the end of the condition
while (tok2 && tok2->str() != ";") {
if (tok2->str() == "(")
tok2 = tok2->link();
else if (tok2->str() == ")") // unexpected ")" => break
break;
tok2 = tok2->next();
}
if (!tok2 || tok2->str() != ";")
return;
const bool hasFor3 = tok2->next()->str() != ")";
if (hasFor3 && !for3(tok2->next(), counter_varid, min_counter_value, max_counter_value, maxMinFlipped))
return;
if (Token::Match(tok2->next(), "%var% =") && MathLib::toLongNumber(max_counter_value) < size)
condition_out_of_bounds = false;
// Goto the end parentheses of the for-statement: "for (x; y; z)" ..
tok2 = tok->next()->link();
if (!tok2 || !tok2->tokAt(5)) {
bailout = true;
return;
}
// Check is the counter variable increased elsewhere inside the loop or used
// for anything else except reading
if (for_bailout(tok2->next(), counter_varid)) {
bailout = true;
return;
}
parse_for_body(tok2->next(), arrayInfo, counter_name, condition_out_of_bounds, counter_varid, min_counter_value, max_counter_value);
}
void CheckBufferOverrun::arrayIndexInForLoop(const Token *tok, const ArrayInfo &arrayInfo)
{
const MathLib::bigint size = arrayInfo.num(0);
const Token *tok3 = tok->tokAt(2);
std::string counter_name;
unsigned int counter_varid = 0;
std::string counter_init_value;
tok3 = for_init(tok3, counter_varid, counter_name, counter_init_value);
if (tok3 == 0 && !counter_name.empty())
_tokenizer->getSymbolDatabase()->debugMessage(tok, "for loop variable \'" + counter_name + "\' has varid 0.");
if (tok3 == 0 || counter_varid == 0)
return;
bool maxMinFlipped = false;
std::string min_counter_value = counter_init_value;
std::string max_counter_value;
if (!for_condition(tok3, counter_varid, min_counter_value, max_counter_value, maxMinFlipped))
return;
const MathLib::bigint max_value = MathLib::toLongNumber(max_counter_value);
// Skip condition
while (tok3 && tok3->str() != ";")
tok3 = tok3->next();
if (max_value > size && Token::simpleMatch(tok3, "; ) {")) {
const Token * const endToken = tok3->linkAt(2);
const Token *useToken = nullptr;
bool incrementInLoop = false;
for (const Token *loopTok = tok3->tokAt(3); loopTok != endToken; loopTok = loopTok->next()) {
if (Token::Match(loopTok, "%varid% [ %var% ++| ]", arrayInfo.declarationId()) && loopTok->tokAt(2)->varId() == counter_varid)
useToken = loopTok;
if (Token::Match(loopTok, "%varid% ++", counter_varid))
incrementInLoop = true;
}
if ((useToken != nullptr) && incrementInLoop)
bufferOverrunError(useToken, arrayInfo.varname());
}
}
void CheckBufferOverrun::checkScope(const Token *tok, const std::vector<std::string> &varname, const ArrayInfo &arrayInfo)
{
const MathLib::bigint size = arrayInfo.num(0);
if (size == 0) // unknown size
return;
if (tok->str() == "return") {
tok = tok->next();
if (!tok)
return;
}
const MathLib::bigint total_size = arrayInfo.element_size() * size;
const unsigned int declarationId = arrayInfo.declarationId();
std::string varnames;
for (unsigned int i = 0; i < varname.size(); ++i)
varnames += (i == 0 ? "" : " . ") + varname[i];
const unsigned char varcount = static_cast<unsigned char>(varname.empty() ? 0U : (varname.size() - 1) * 2U);
// ValueFlow array index..
if ((declarationId > 0 && Token::Match(tok, "%varid% [", declarationId)) ||
(declarationId == 0 && Token::Match(tok, (varnames + " [").c_str()))) {
const Token *tok2 = tok;
while (tok2->str() != "[")
tok2 = tok2->next();
valueFlowCheckArrayIndex(tok2, arrayInfo);
}
// If the result of pointer arithmetic means that the pointer is
// out of bounds then this flag will be set.
bool pointerIsOutOfBounds = false;
const bool isPortabilityEnabled = _settings->isEnabled("portability");
for (const Token* const end = tok->scope()->classEnd; tok != end; tok = tok->next()) {
if (declarationId != 0 && Token::Match(tok, "%varid% = new|malloc|realloc", declarationId)) {
// Abort
break;
}
// reassign buffer
if (declarationId > 0 && Token::Match(tok, "[;{}] %varid% = %any%", declarationId)) {
// using varid .. bailout
if (tok->tokAt(3)->varId() != declarationId)
break;
pointerIsOutOfBounds = false;
}
// Array index..
if ((declarationId > 0 && ((tok->str() == "return" || (!tok->isName() && !Token::Match(tok, "[.&]"))) && Token::Match(tok->next(), "%varid% [ %num% ]", declarationId))) ||
(declarationId == 0 && ((tok->str() == "return" || (!tok->isName() && !Token::Match(tok, "[.&]"))) && (Token::Match(tok->next(), (varnames + " [ %num% ]").c_str()) || Token::Match(tok->next(), (varname[0] +" [ %num% ] . " + varname[1] + " [ %num% ]").c_str()))))) {
std::vector<MathLib::bigint> indexes;
const Token *tok2 = tok->tokAt(2 + varcount);
for (; Token::Match(tok2, "[ %num% ]"); tok2 = tok2->tokAt(3)) {
const MathLib::bigint index = MathLib::toLongNumber(tok2->strAt(1));
indexes.push_back(index);
}
for (; Token::Match(tok2->tokAt(3), "[ %num% ]"); tok2 = tok2->tokAt(3)) {
const MathLib::bigint index = MathLib::toLongNumber(tok2->strAt(4));
indexes.push_back(index);
}
if (indexes.size() == arrayInfo.num().size()) {
// Check if the indexes point outside the whole array..
// char a[10][10];
// a[0][20] <-- ok.
// a[9][20] <-- error.
// total number of elements of array..
MathLib::bigint totalElements = 1;
// total index..
MathLib::bigint totalIndex = 0;
// calculate the totalElements and totalIndex..
for (unsigned int i = 0; i < indexes.size(); ++i) {
std::size_t ri = indexes.size() - 1 - i;
totalIndex += indexes[ri] * totalElements;
totalElements *= arrayInfo.num(ri);