scc

commit 1ea33a55b6d3df7fd73194f0f2a599960c67676e
parent e4c9da7e693f8c2ad9008ad2c895654d563905fe
Author: Roberto E. Vargas Caballero <k0ga@shike2.com>
Date:   Tue, 18 Aug 2015 14:16:10 +0200

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).

Diffstat:
M
cc1/decl.c
 | 
12
++++++++++++
M
cc1/expr.c
 | 
4
++++
M
cc1/stmt.c
 | 
8
++++++++

3 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/cc1/decl.c b/cc1/decl.c
@@ -207,9 +207,14 @@ static void
 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 @@ structdcl(void)
 {
 	Symbol *sym;
 	Type *tp;
+	static int nested;
 
 	sym = newtag();
 	tp = sym->type;
@@ -419,8 +425,14 @@ structdcl(void)
 		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;
 }
 
diff --git 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 @@ cast(void)
 {
 	Node *lp, *rp;
 	Type *tp;
+	static int nested;
 
 	if (!accept('('))
 		return unary();
@@ -893,6 +895,8 @@ cast(void)
 		}
 		break;
 	default:
+		if (nested == NR_SUBEXPR)
+			error("too expressions nested by parentheses");
 		rp = expr();
 		expect(')');
 		rp = postfix(rp);
diff --git 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 @@ blockit(Symbol *lbreak, Symbol *lcont, Caselist *lswitch)
 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();
 	/*