udhcpc: check read of option length byte to be within packet

function                                             old     new   delta
udhcp_get_option                                     215     220      +5
udhcp_run_script                                     802     803      +1

Signed-off-by: Brian Foley <bpfoley@google.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index bef7327..1c10511 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -450,7 +450,7 @@
 			temp = udhcp_get_option(packet, i);
 			if (temp) {
 				if (i == DHCP_OPTION_OVERLOAD)
-					overload = *temp;
+					overload |= *temp;
 				else if (i == DHCP_SUBNET)
 					envc++; /* for $mask */
 				envc++;
@@ -476,7 +476,7 @@
 	 * uint16_t secs;   // elapsed since client began acquisition/renewal
 	 * uint16_t flags;  // only one flag so far: bcast. Never set by server
 	 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
-	 *                  // if during renew server wants to give us differn IP?)
+	 *                  // if during renew server wants to give us different IP?)
 	 * uint32_t gateway_nip; // relay agent IP address
 	 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
 	 * TODO: export gateway_nip as $giaddr?