From f9beeb22e2a4128ed85a8dc267d0823e5cfd3f47 Mon Sep 17 00:00:00 2001 From: Brian Foley Date: Tue, 25 Oct 2016 14:20:55 +0200 Subject: 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 Signed-off-by: Denys Vlasenko --- networking/udhcp/common.c | 8 +++++++- networking/udhcp/dhcpc.c | 4 ++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index 0cf4dab63..589bcd674 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -226,9 +226,12 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) 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 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code) } 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 bef73277a..1c1051107 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -450,7 +450,7 @@ static char **fill_envp(struct dhcp_packet *packet) 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 @@ static char **fill_envp(struct dhcp_packet *packet) * 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? -- cgit v1.2.3