int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
{
	struct option_set **opt_list = arg;
	char *opt, *val;
	char *str;
	const struct dhcp_optflag *optflag;
	struct dhcp_optflag bin_optflag;
	unsigned optcode;
	int retval, length;
	/* IP_PAIR needs 8 bytes, STATIC_ROUTES needs 9 max */
	char buffer[9] ALIGNED(4);
	uint16_t *result_u16 = (uint16_t *) buffer;
	uint32_t *result_u32 = (uint32_t *) buffer;

	/* Cheat, the only *const* str possible is "" */
	str = (char *) const_str;
	opt = strtok(str, " \t=");
	if (!opt)
		return 0;

	optcode = bb_strtou(opt, NULL, 0);
	if (!errno && optcode < 255) {
		/* Raw (numeric) option code */
		bin_optflag.flags = OPTION_BIN;
		bin_optflag.code = optcode;
		optflag = &bin_optflag;
	} else {
		optflag = &dhcp_optflags[udhcp_option_idx(opt)];
	}

	retval = 0;
	do {
		val = strtok(NULL, ", \t");
		if (!val)
			break;
		length = dhcp_option_lengths[optflag->flags & OPTION_TYPE_MASK];
		retval = 0;
		opt = buffer; /* new meaning for variable opt */
		switch (optflag->flags & OPTION_TYPE_MASK) {
		case OPTION_IP:
			retval = udhcp_str2nip(val, buffer);
			break;
		case OPTION_IP_PAIR:
			retval = udhcp_str2nip(val, buffer);
			val = strtok(NULL, ", \t/-");
			if (!val)
				retval = 0;
			if (retval)
				retval = udhcp_str2nip(val, buffer + 4);
			break;
		case OPTION_STRING:
		case OPTION_STRING_HOST:
#if ENABLE_FEATURE_UDHCP_RFC3397
		case OPTION_DNS_STRING:
#endif
			length = strnlen(val, 254);
			if (length > 0) {
				opt = val;
				retval = 1;
			}
			break;
		case OPTION_U8:
			buffer[0] = bb_strtou32(val, NULL, 0);
			retval = (errno == 0);
			break;
		/* htonX are macros in older libc's, using temp var
		 * in code below for safety */
		/* TODO: use bb_strtoX? */
		case OPTION_U16: {
			uint32_t tmp = bb_strtou32(val, NULL, 0);
			*result_u16 = htons(tmp);
			retval = (errno == 0 /*&& tmp < 0x10000*/);
			break;
		}
		case OPTION_U32: {
			uint32_t tmp = bb_strtou32(val, NULL, 0);
			*result_u32 = htonl(tmp);
			retval = (errno == 0);
			break;
		}
		case OPTION_S32: {
			int32_t tmp = bb_strtoi32(val, NULL, 0);
			*result_u32 = htonl(tmp);
			retval = (errno == 0);
			break;
		}
		case OPTION_STATIC_ROUTES: {
			/* Input: "a.b.c.d/m" */
			/* Output: mask(1 byte),pfx(0-4 bytes),gw(4 bytes) */
			unsigned mask;
			char *slash = strchr(val, '/');
			if (slash) {
				*slash = '\0';
				retval = udhcp_str2nip(val, buffer + 1);
				buffer[0] = mask = bb_strtou(slash + 1, NULL, 10);
				val = strtok(NULL, ", \t/-");
				if (!val || mask > 32 || errno)
					retval = 0;
				if (retval) {
					length = ((mask + 7) >> 3) + 5;
					retval = udhcp_str2nip(val, buffer + (length - 4));
				}
			}
			break;
		}
		case OPTION_BIN: /* handled in attach_option() */
			opt = val;
			retval = 1;
		default:
			break;
		}
		if (retval)
			attach_option(opt_list, optflag, opt, length);
	} while (retval && (optflag->flags & OPTION_LIST));

	return retval;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.