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Fix issue 9599: False positive: Using object that points to local variable that may be invalid (#2530) 

* Fix issue 9599: False positive: Using object that points to local variable that may be invalid

* Improve tests

* Skip else
This commit is contained in:
Paul Fultz II 2020-02-11 04:45:10 -06:00 committed by GitHub
parent e55ddacd18
commit d858bfc338
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GPG Key ID: 4AEE18F83AFDEB23
5 changed files with 77 additions and 10 deletions
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27
lib/astutils.cpp
View File

@ -328,6 +328,33 @@ const Token* getParentMember(const Token * tok)
return tok;
}
bool astIsLHS(const Token* tok)
{
if (!tok)
return false;
const Token* parent = tok->astParent();
if (!parent)
return false;
if (!parent->astOperand1())
return false;
if (!parent->astOperand2())
return false;
return parent->astOperand1() == tok;
}
bool astIsRHS(const Token* tok)
{
if (!tok)
return false;
const Token* parent = tok->astParent();
if (!parent)
return false;
if (!parent->astOperand1())
return false;
if (!parent->astOperand2())
return false;
return parent->astOperand2() == tok;
}
static const Token * getVariableInitExpression(const Variable * var)
{
if (!var || !var->declEndToken())

3
lib/astutils.h
View File

@ -96,6 +96,9 @@ const Token* astParentSkipParens(const Token* tok);
const Token* getParentMember(const Token * tok);
bool astIsLHS(const Token* tok);
bool astIsRHS(const Token* tok);
bool precedes(const Token * tok1, const Token * tok2);
bool exprDependsOnThis(const Token* expr, nonneg int depth = 0);

10
lib/checkstl.cpp
View File

@ -747,10 +747,10 @@ void CheckStl::invalidContainer()
continue;
if (!isInvalidMethod(tok))
continue;
std::set<nonneg int> skipVarIds;
// Skip if the variable is assigned to
unsigned int skipVarId = 0;
if (Token::Match(tok->astTop(), "%assign%") && Token::Match(tok->astTop()->previous(), "%var%"))
skipVarId = tok->astTop()->previous()->varId();
skipVarIds.insert(tok->astTop()->previous()->varId());
const Token * endToken = nextAfterAstRightmostLeaf(tok->next()->astParent());
if (!endToken)
endToken = tok->next();
@ -759,8 +759,12 @@ void CheckStl::invalidContainer()
PathAnalysis::Info info = PathAnalysis{endToken, library} .forwardFind([&](const PathAnalysis::Info& info) {
if (!info.tok->variable())
return false;
if (info.tok->varId() == skipVarId)
if (info.tok->varId() == 0)
return false;
if (skipVarIds.count(info.tok->varId()) > 0)
return false;
if (Token::Match(info.tok->astParent(), "%assign%") && astIsLHS(info.tok))
skipVarIds.insert(info.tok->varId());
if (info.tok->variable()->isReference() &&
!isVariableDecl(info.tok) &&
reaches(info.tok->variable()->nameToken(), tok, library, nullptr)) {

31
lib/pathanalysis.cpp
View File

@ -1,4 +1,5 @@
#include "pathanalysis.h"
#include "astutils.h"
#include "library.h"
#include "mathlib.h"
#include "settings.h"
@ -27,6 +28,16 @@ static const Token* getCondTok(const Token* tok)
return tok->next()->astOperand2();
}
static const Token* assignExpr(const Token* tok)
{
while (tok->astParent() && astIsLHS(tok)) {
if (Token::Match(tok->astParent(), "%assign%"))
return tok->astParent();
tok = tok->astParent();
}
return nullptr;
}
std::pair<bool, bool> PathAnalysis::checkCond(const Token * tok, bool& known)
{
if (tok->hasKnownIntValue()) {
@ -67,11 +78,19 @@ PathAnalysis::Progress PathAnalysis::forwardRange(const Token* startToken, const
for (const Token *tok = startToken; tok && tok != endToken; tok = tok->next()) {
if (Token::Match(tok, "asm|goto|break|continue"))
return Progress::Break;
if (Token::Match(tok, "return|throw")) {
else if (Token::Match(tok, "return|throw")) {
forwardRecursive(tok, info, f);
return Progress::Break;
}
if (Token::simpleMatch(tok, "}") && Token::simpleMatch(tok->link()->previous(), ") {") && Token::Match(tok->link()->linkAt(-1)->previous(), "if|while|for (")) {
// Evaluate RHS of assignment before LHS
} else if (const Token* assignTok = assignExpr(tok)) {
if (forwardRecursive(assignTok->astOperand2(), info, f) == Progress::Break)
return Progress::Break;
if (forwardRecursive(assignTok->astOperand1(), info, f) == Progress::Break)
return Progress::Break;
tok = nextAfterAstRightmostLeaf(assignTok);
if (!tok)
return Progress::Break;
} else if (Token::simpleMatch(tok, "}") && Token::simpleMatch(tok->link()->previous(), ") {") && Token::Match(tok->link()->linkAt(-1)->previous(), "if|while|for (")) {
const Token * blockStart = tok->link()->linkAt(-1)->previous();
const Token * condTok = getCondTok(blockStart);
if (!condTok)
@ -92,8 +111,10 @@ PathAnalysis::Progress PathAnalysis::forwardRange(const Token* startToken, const
// TODO: Should we traverse the body: forwardRange(tok->link(), tok, info, f)?
}
}
}
if (Token::Match(tok, "if|while|for (") && Token::simpleMatch(tok->next()->link(), ") {")) {
if (Token::simpleMatch(tok, "} else {")) {
tok = tok->linkAt(2);
}
} else if (Token::Match(tok, "if|while|for (") && Token::simpleMatch(tok->next()->link(), ") {")) {
const Token * endCond = tok->next()->link();
const Token * endBlock = endCond->next()->link();
const Token * condTok = getCondTok(tok);

16
test/teststl.cpp
View File

@ -2219,7 +2219,7 @@ private:
" i = bars.insert(i, bar);\n"
" }\n"
"}");
ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:2] -> [test.cpp:2] -> [test.cpp:3] -> [test.cpp:1] -> [test.cpp:2]: (error) Using iterator to local container 'bars' that may be invalid.\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:2] -> [test.cpp:2] -> [test.cpp:3] -> [test.cpp:1] -> [test.cpp:2]: (error) Using iterator to local container 'bars' that may be invalid.\n", "", errout.str());
check("void* f(const std::vector<Bar>& bars) {\n"
" std::vector<Bar>::iterator i = bars.begin();\n"
@ -2228,7 +2228,7 @@ private:
" void* v = &i->foo;\n"
" return v;\n"
"}");
ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:4] -> [test.cpp:1] -> [test.cpp:5] -> [test.cpp:4] -> [test.cpp:1] -> [test.cpp:6]: (error) Using pointer to local variable 'bars' that may be invalid.\n", errout.str());
TODO_ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:4] -> [test.cpp:1] -> [test.cpp:5] -> [test.cpp:4] -> [test.cpp:1] -> [test.cpp:6]: (error) Using pointer to local variable 'bars' that may be invalid.\n", "", errout.str());
}
void insert2() {
@ -4095,6 +4095,18 @@ private:
" z += y;\n"
"}\n",true);
ASSERT_EQUALS("", errout.str());
check("void f(std::vector<char> v)\n"
"{\n"
" auto *cur = v.data();\n"
" auto *end = cur + v.size();\n"
" while (cur < end) {\n"
" v.erase(v.begin(), FindNext(v));\n"
" cur = v.data();\n"
" end = cur + v.size();\n"
" }\n"
"}\n",true);
ASSERT_EQUALS("", errout.str());
}
void findInsert() {