shithub: libmujs

Info  •  Files  •  Log  •  Branches

Issue #162: Check stack overflow during regexp compilation.

Only bother checking during the first compilation pass that counts
the size of the program.

--- a/regexp.c

+++ b/regexp.c

@@ -622,25 +622,26 @@

 	Reinst *y;

 };

-static int count(struct cstate *g, Renode *node)

+static int count(struct cstate *g, Renode *node, int depth)

 {

 	int min, max, n;

 	if (!node) return 0;

+	if (++depth > REG_MAXREC) die(g, "stack overflow");

 	switch (node->type) {

 	default: return 1;

-	case P_CAT: return count(g, node->x) + count(g, node->y);

-	case P_ALT: return count(g, node->x) + count(g, node->y) + 2;

+	case P_CAT: return count(g, node->x, depth) + count(g, node->y, depth);

+	case P_ALT: return count(g, node->x, depth) + count(g, node->y, depth) + 2;

 	case P_REP:

 		min = node->m;

 		max = node->n;

-		if (min == max) n = count(g, node->x) * min;

-		else if (max < REPINF) n = count(g, node->x) * max + (max - min);

-		else n = count(g, node->x) * (min + 1) + 2;

+		if (min == max) n = count(g, node->x, depth) * min;

+		else if (max < REPINF) n = count(g, node->x, depth) * max + (max - min);

+		else n = count(g, node->x, depth) * (min + 1) + 2;

 		if (n < 0 || n > REG_MAXPROG) die(g, "program too large");

 		return n;

-	case P_PAR: return count(g, node->x) + 2;

-	case P_PLA: return count(g, node->x) + 2;

-	case P_NLA: return count(g, node->x) + 2;

+	case P_PAR: return count(g, node->x, depth) + 2;

+	case P_PLA: return count(g, node->x, depth) + 2;

+	case P_NLA: return count(g, node->x, depth) + 2;

 	}

 }

@@ -903,7 +904,7 @@

 	putchar('\n');

 #endif

-	n = 6 + count(&g, node);

+	n = 6 + count(&g, node, 0);

 	if (n < 0 || n > REG_MAXPROG)

 		die(&g, "program too large");