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Check for cycles in AST when adding nodes to prevent hangs from cyclic ASTs (#3329)

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Paul Fultz II 2021-07-07 01:21:35 -05:00 committed by GitHub
parent 3b9c399f72
commit 5825a35566
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 18 additions and 13 deletions
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31
lib/token.cpp
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@ -1340,18 +1340,29 @@ std::string Token::stringifyList(bool varid) const
return stringifyList(varid, false, true, true, true, nullptr, nullptr); return stringifyList(varid, false, true, true, true, nullptr, nullptr);
} }
static Token* checkAstCycle(Token* tok)
{
std::set<const Token*> visited;
visitAstNodes(tok, [&](const Token* child) {
if (!visited.insert(child).second)
throw InternalError(child, "Internal error. AST cyclic dependency.");
return ChildrenToVisit::op1_and_op2;
});
while (tok->astParent()) {
if (!visited.insert(tok->astParent()).second) // #6838/#6726/#8352 avoid hang on garbage code
throw InternalError(tok, "Internal error. AST cyclic dependency.");
tok = tok->astParent();
}
return tok;
}
void Token::astOperand1(Token *tok) void Token::astOperand1(Token *tok)
{ {
if (mImpl->mAstOperand1) if (mImpl->mAstOperand1)
mImpl->mAstOperand1->mImpl->mAstParent = nullptr; mImpl->mAstOperand1->mImpl->mAstParent = nullptr;
// goto parent operator // goto parent operator
if (tok) { if (tok) {
std::set<Token*> visitedParents; tok = checkAstCycle(tok);
while (tok->mImpl->mAstParent) {
if (!visitedParents.insert(tok->mImpl->mAstParent).second) // #6838/#6726/#8352 avoid hang on garbage code
throw InternalError(this, "Internal error. Token::astOperand1() cyclic dependency.");
tok = tok->mImpl->mAstParent;
}
tok->mImpl->mAstParent = this; tok->mImpl->mAstParent = this;
} }
mImpl->mAstOperand1 = tok; mImpl->mAstOperand1 = tok;
@ -1363,13 +1374,7 @@ void Token::astOperand2(Token *tok)
mImpl->mAstOperand2->mImpl->mAstParent = nullptr; mImpl->mAstOperand2->mImpl->mAstParent = nullptr;
// goto parent operator // goto parent operator
if (tok) { if (tok) {
std::set<Token*> visitedParents; tok = checkAstCycle(tok);
while (tok->mImpl->mAstParent) {
//std::cout << tok << " -> " << tok->mAstParent ;
if (!visitedParents.insert(tok->mImpl->mAstParent).second) // #6838/#6726 avoid hang on garbage code
throw InternalError(this, "Internal error. Token::astOperand2() cyclic dependency.");
tok = tok->mImpl->mAstParent;
}
tok->mImpl->mAstParent = this; tok->mImpl->mAstParent = this;
} }
mImpl->mAstOperand2 = tok; mImpl->mAstOperand2 = tok;