host: Prevent overflow in host_create_netmask() if mask is 0 or 32/128

2013-07-24 16:17:03 +02:00
parent a00ac1d9ee
commit 6e2ec33f9d
1 changed files with 7 additions and 5 deletions
@@ -597,13 +597,15 @@ host_t *host_create_netmask(int family, int netbits)
 	this->address.sa_family = family;
 	update_sa_len(this);

-	bytes = (netbits + 7) / 8;
-	bits = (bytes * 8) - netbits;
+	bytes = netbits / 8;
+	bits = 8 - (netbits & 0x07);

 	memset(target, 0xff, bytes);
-	memset(target + bytes, 0x00, len - bytes);
-	target[bytes - 1] = bits ? (u_int8_t)(0xff << bits) : 0xff;
-
+	if (bytes < len)
+	{
+		memset(target + bytes, 0x00, len - bytes);
+		target[bytes] = (u_int8_t)(0xff << bits);
+	}
 	return &this->public;
 }