From 74d9f1ba37010face4bd1449df4d60dd84450b06 Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Mon, 7 Jan 2019 15:33:42 +0100
Subject: [PATCH] udhcpc: when decoding DHCP_SUBNET, ensure it is 4 bytes long

function                                             old     new   delta
udhcp_run_script                                     795     801      +6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

Upstream-Status: Backport
CVE: CVE-2019-5747
Affects < 1.30.0
Signed-off-by: Armin Kuster <akuster@mvista.com>

---
 networking/udhcp/common.c | 2 +-
 networking/udhcp/common.h | 2 +-
 networking/udhcp/dhcpc.c  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

Index: busybox-1.29.3/networking/udhcp/common.c
===================================================================
--- busybox-1.29.3.orig/networking/udhcp/common.c
+++ busybox-1.29.3/networking/udhcp/common.c
@@ -300,7 +300,7 @@ uint8_t* FAST_FUNC udhcp_get_option32(st
 {
 	uint8_t *r = udhcp_get_option(packet, code);
 	if (r) {
-		if (r[-1] != 4)
+		if (r[-OPT_DATA + OPT_LEN] != 4)
 			r = NULL;
 	}
 	return r;
Index: busybox-1.29.3/networking/udhcp/common.h
===================================================================
--- busybox-1.29.3.orig/networking/udhcp/common.h
+++ busybox-1.29.3/networking/udhcp/common.h
@@ -119,7 +119,7 @@ enum {
 //#define DHCP_TIME_SERVER      0x04 /* RFC 868 time server (32-bit, 0 = 1.1.1900) */
 //#define DHCP_NAME_SERVER      0x05 /* IEN 116 _really_ ancient kind of NS */
 //#define DHCP_DNS_SERVER       0x06
-//#define DHCP_LOG_SERVER       0x07 /* port 704 UDP log (not syslog)
+//#define DHCP_LOG_SERVER       0x07 /* port 704 UDP log (not syslog) */
 //#define DHCP_COOKIE_SERVER    0x08 /* "quote of the day" server */
 //#define DHCP_LPR_SERVER       0x09
 #define DHCP_HOST_NAME          0x0c /* either client informs server or server gives name to client */
Index: busybox-1.29.3/networking/udhcp/dhcpc.c
===================================================================
--- busybox-1.29.3.orig/networking/udhcp/dhcpc.c
+++ busybox-1.29.3/networking/udhcp/dhcpc.c
@@ -526,7 +526,7 @@ static char **fill_envp(struct dhcp_pack
 		temp = udhcp_get_option(packet, code);
 		*curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
 		putenv(*curr++);
-		if (code == DHCP_SUBNET) {
+		if (code == DHCP_SUBNET && temp[-OPT_DATA + OPT_LEN] == 4) {
 			/* Subnet option: make things like "$ip/$mask" possible */
 			uint32_t subnet;
 			move_from_unaligned32(subnet, temp);
