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Fixed #4482 (add test for UB due to usage of NULL in variadic functions)

This commit is contained in:
Daniel Marjamäki 2013-01-13 12:02:10 +01:00
parent b538c50856
commit 2e56928834
6 changed files with 112 additions and 8 deletions
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82
lib/checkother.cpp
View File

@ -3748,3 +3748,85 @@ void CheckOther::oppositeInnerConditionError(const Token *tok)
{
reportError(tok, Severity::warning, "oppositeInnerCondition", "Opposite conditions in nested 'if' blocks lead to a dead code block.", true);
}
void CheckOther::checkVarFuncNullUB()
{
if (!_settings->isEnabled("portability"))
return;
const SymbolDatabase *symbolDatabase = _tokenizer->getSymbolDatabase();
const std::size_t functions = symbolDatabase->functionScopes.size();
for (std::size_t i = 0; i < functions; ++i) {
const Scope * scope = symbolDatabase->functionScopes[i];
for (const Token* tok = scope->classStart; tok != scope->classEnd; tok = tok->next()) {
// Is NULL passed to a function?
if (Token::Match(tok,"[(,] NULL [,)]")) {
// Locate function name in this function call.
const Token *ftok = tok;
while (ftok && ftok->str() != "(") {
if (ftok->str() == ")")
ftok = ftok->link();
ftok = ftok->previous();
}
ftok = ftok ? ftok->previous() : NULL;
if (ftok && ftok->isName()) {
// If this is a variadic function then report error
const Function *f = symbolDatabase->findFunctionByName(ftok->str(), scope);
if (f) {
const Token *tok2 = f->argDef;
tok2 = tok2 ? tok2->link() : NULL; // goto ')'
if (Token::simpleMatch(tok2->tokAt(-3), ". . ."))
varFuncNullUBError(tok);
}
}
}
}
}
}
void CheckOther::varFuncNullUBError(const Token *tok)
{
reportError(tok,
Severity::portability,
"varFuncNullUB",
"Passing NULL to a function with variable number of arguments leads to undefined behaviour on some platforms.\n"
"Passing NULL to a function with variable number of arguments leads to undefined behaviour on some platforms.\n"
"The behaviour is undefined when NULL is #defined as 0, sizeof(int)!=sizeof(void*) and the function expects a pointer. Otherwise the behaviour is defined.\n"
"See section section 7.1.4 and section 7.15.1.1 in the C standard. Section 7.1.4 explains that the function call is UB. Section 7.15.1.1 explains that the va_arg macro has UB.\n"
"To reproduce you might be able to use this little code example. Try it on a platform where sizeof(int)!=sizeof(void*), for instance on a x86_64 machine. If ERROR is written by the program on the screen it means that 0 is not converted to a NULL pointer. Changing the 0 to (void*)0 will fix the program.\n"
"#include <stdarg.h>\n"
"#include <stdio.h>\n"
"\n"
"void f(char *s, ...) {\n"
" va_list ap;\n"
" va_start(ap,s);\n"
" for (;;) {\n"
" char *p = va_arg(ap,char*);\n"
" printf(\"%018p, %s\n\", p, (long)p & 255 ? p : \"\");\n"
" if(!p) break;\n"
" }\n"
" va_end(ap);\n"
"}\n"
"\n"
"void g() {\n"
" char *s2 = \"x\";\n"
" char *s3 = \"ERROR\";\n"
"\n"
" // changing 0 to 0L makes the error go away on x86_64\n"
" f(\"first\", s2, s2, s2, s2, s2, 0, s3, (char*)0);\n"
"}\n"
"\n"
"void h() {\n"
" int i;\n"
" volatile unsigned char a[1000];\n"
" for (i = 0; i<sizeof(a); i++)\n"
" a[i] = -1;\n"
"}\n"
"\n"
"int main() {\n"
" h();\n"
" g();\n"
" return 0;\n"
"}");
}

9
lib/checkother.h
View File

@ -80,6 +80,7 @@ public:
checkOther.checkSignOfUnsignedVariable(); // don't ignore casts (#3574)
checkOther.checkIncompleteArrayFill();
checkOther.checkSuspiciousStringCompare();
checkOther.checkVarFuncNullUB();
}
/** @brief Run checks against the simplified token list */
@ -285,6 +286,9 @@ public:
/** @brief %Check for buffers that are filled incompletely with memset and similar functions */
void checkIncompleteArrayFill();
/** @brief %Check that variadic function calls don't use NULL. If NULL is #defined as 0 and the function expects a pointer, the behaviour is undefined. */
void checkVarFuncNullUB();
private:
// Error messages..
void oppositeInnerConditionError(const Token *tok);
@ -354,6 +358,7 @@ private:
void negativeBitwiseShiftError(const Token *tok);
void redundantCopyError(const Token *tok, const std::string &varname);
void incompleteArrayFillError(const Token* tok, const std::string& buffer, const std::string& function, bool boolean);
void varFuncNullUBError(const Token *tok);
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
CheckOther c(0, settings, errorLogger);
@ -428,6 +433,7 @@ private:
c.cctypefunctionCallError(0, "funname", "value");
c.moduloAlwaysTrueFalseError(0, "1");
c.incompleteArrayFillError(0, "buffer", "memset", false);
c.varFuncNullUBError(0);
}
static std::string myName() {
@ -495,7 +501,8 @@ private:
"* Suspicious use of ; at the end of 'if/for/while' statement.\n"
"* incorrect usage of functions from ctype library.\n"
"* Comparisons of modulo results that are always true/false.\n"
"* Array filled incompletely using memset/memcpy/memmove.\n";
"* Array filled incompletely using memset/memcpy/memmove.\n"
"* Passing NULL pointer to function with variable number of arguments leads to UB on some platforms.\n";
}
void checkExpressionRange(const std::list<const Function*> &constFunctions,

10
lib/tokenize.cpp
View File

@ -2131,15 +2131,15 @@ void Tokenizer::simplifyFileAndLineMacro()
void Tokenizer::simplifyNull()
{
for (Token *tok = list.front(); tok; tok = tok->next()) {
if (tok->str() == "NULL" || tok->str() == "__null" ||
tok->str() == "'\\0'" || tok->str() == "'\\x0'") {
if (tok->str() == "NULL" && !Token::Match(tok->previous(), "[(,] NULL [,)]"))
tok->str("0");
} else if (tok->isNumber() &&
else if (tok->str() == "__null" || tok->str() == "'\\0'" || tok->str() == "'\\x0'")
tok->str("0");
else if (tok->isNumber() &&
MathLib::isInt(tok->str()) &&
MathLib::toLongNumber(tok->str()) == 0) {
MathLib::toLongNumber(tok->str()) == 0)
tok->str("0");
}
}
// nullptr..
if (isCPP() && _settings->standards.cpp == Standards::CPP11) {

8
test/testother.cpp
View File

@ -188,6 +188,8 @@ private:
TEST_CASE(redundantVarAssignment);
TEST_CASE(redundantMemWrite);
TEST_CASE(varFuncNullUB);
}
void check(const char code[], const char *filename = NULL, bool experimental = false, bool inconclusive = true) {
@ -6799,6 +6801,12 @@ private:
"}");
ASSERT_EQUALS("", errout.str());
}
void varFuncNullUB() { // #4482
check("void a(...);\n"
"void b() { a(NULL); }");
ASSERT_EQUALS("[test.cpp:2]: (portability) Passing NULL to a function with variable number of arguments leads to undefined behaviour on some platforms.\n", errout.str());
}
};
REGISTER_TEST(TestOther)

2
test/testsimplifytokens.cpp
View File

@ -3407,7 +3407,7 @@ private:
ASSERT_EQUALS("void f ( int i ) { goto label ; { label : ; " + *it + " ; } }",tok("void f (int i) { goto label; switch(i) { label: " + *it + "; } }"));
//ticket #3148
ASSERT_EQUALS("void f ( ) { MACRO ( " + *it + " ) }",tok("void f() { MACRO(" + *it + ") }"));
ASSERT_EQUALS("void f ( ) { MACRO ( " + *it + " ; , 0 ) }",tok("void f() { MACRO(" + *it + ";, NULL) }"));
ASSERT_EQUALS("void f ( ) { MACRO ( " + *it + " ; , NULL ) }",tok("void f() { MACRO(" + *it + ";, NULL) }"));
ASSERT_EQUALS("void f ( ) { MACRO ( bar1 , " + *it + " ) }",tok("void f() { MACRO(bar1, " + *it + ") }"));
ASSERT_EQUALS("void f ( ) { MACRO ( " + *it + " ; bar2 , foo ) }",tok("void f() { MACRO(" + *it + "; bar2, foo) }"));
}

7
test/testtokenize.cpp
View File

@ -448,6 +448,8 @@ private:
TEST_CASE(simplifyOperatorName5);
TEST_CASE(simplifyOperatorName6); // ticket #3194
TEST_CASE(simplifyNull);
TEST_CASE(simplifyNullArray);
// Some simple cleanups of unhandled macros in the global scope
@ -7207,6 +7209,11 @@ private:
ASSERT_EQUALS(result2, tokenizeAndStringify(code2,false));
}
void simplifyNull() {
ASSERT_EQUALS("if ( p == 0 )", tokenizeAndStringify("if (p==NULL)"));
ASSERT_EQUALS("f ( NULL ) ;", tokenizeAndStringify("f(NULL);"));
}
void simplifyNullArray() {
ASSERT_EQUALS("* ( foo . bar [ 5 ] ) = x ;", tokenizeAndStringify("0[foo.bar[5]] = x;"));
}