shithub: scc

Info  •  Files  •  Log  •  Branches

Limit the recursivity in declarations and expressions

Recursivity can generate a segfault or a heap-stack collition,
so it is a good idea limiting it with the values proposed by
c89 standard (if your code have more of 32 parentheses nested
try to use a lisp interpreter).

--- a/cc1/decl.c

+++ b/cc1/decl.c

@@ -207,9 +207,14 @@

 directdcl(struct declarators *dp, unsigned ns)

 {

 	Symbol *sym;

+	static int nested;

 	if (accept('(')) {

+		if (nested == NR_SUBTYPE)

+			error("too declarators nested by parentheses");

+		++nested;

 		declarator(dp, ns);

+		--nested;

 		expect(')');

 	} else {

 		if (yytoken == IDEN || yytoken == TYPEIDEN) {

@@ -409,6 +414,7 @@

 {

 	Symbol *sym;

 	Type *tp;

+	static int nested;

 	sym = newtag();

 	tp = sym->type;

@@ -419,8 +425,14 @@

 		error("redefinition of struct/union '%s'", sym->name);

 	tp->defined = 1;

+	if (nested == NR_STRUCT_LEVEL)

+		error("too levels of nested structure or union definitions");

+

+	++nested;

 	while (!accept('}'))

 		fieldlist(tp);

+	--nested;

+

 	return tp;

 }

--- a/cc1/expr.c

+++ b/cc1/expr.c

@@ -4,6 +4,7 @@

 #include <string.h>

 #include "../inc/cc.h"

+#include "../inc/sizes.h"

 #include "cc1.h"

@@ -870,6 +871,7 @@

 {

 	Node *lp, *rp;

 	Type *tp;

+	static int nested;

 	if (!accept('('))

 		return unary();

@@ -893,6 +895,8 @@

 		}

 		break;

 	default:

+		if (nested == NR_SUBEXPR)

+			error("too expressions nested by parentheses");

 		rp = expr();

 		expect(')');

 		rp = postfix(rp);

--- a/cc1/stmt.c

+++ b/cc1/stmt.c

@@ -5,6 +5,7 @@

 #include <stdio.h>

 #include "../inc/cc.h"

+#include "../inc/sizes.h"

 #include "cc1.h"

 Symbol *curfun;

@@ -297,14 +298,21 @@

 void

 compound(Symbol *lbreak, Symbol *lcont, Caselist *lswitch)

 {

+	static int nested;

+

 	pushctx();

 	expect('{');

+	if (nested == NR_BLOCK)

+		error("too nesting levels of compound statements");

+

+	++nested;

 	for (;;) {

 		if (yytoken == '}')

 			break;

 		blockit(lbreak, lcont, lswitch);

 	}

+	--nested;

 	popctx();

 	/*