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/common.c b/networking/udhcp/common.c
index 0cf4dab..589bcd6 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -226,9 +226,12 @@
rem = sizeof(packet->options);
while (1) {
if (rem <= 0) {
+ complain:
bb_error_msg("bad packet, malformed option field");
return NULL;
}
+
+ /* DHCP_PADDING and DHCP_END have no [len] byte */
if (optionptr[OPT_CODE] == DHCP_PADDING) {
rem--;
optionptr++;
@@ -251,10 +254,13 @@
}
break;
}
+
+ if (rem <= OPT_LEN)
+ goto complain; /* complain and return NULL */
len = 2 + optionptr[OPT_LEN];
rem -= len;
if (rem < 0)
- continue; /* complain and return NULL */
+ goto complain; /* complain and return NULL */
if (optionptr[OPT_CODE] == code) {
log_option("option found", optionptr);
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?