Nokia G21 - Firmware

This is a structured technical paper regarding the , covering its architecture, update mechanism, customization challenges, and security aspects. Title: Analysis of Firmware Architecture and Update Ecosystem for the Nokia G21 (TA-1418) Author: [Generated for Technical Review] Date: April 2026 Subject: Embedded Systems / Mobile Firmware Engineering 1. Abstract The Nokia G21, released in 2022, operates under HMD Global’s “Android One” program. This paper analyzes its firmware structure—specifically the partition layout, bootloader security (unlockability), kernel versioning, and the seamless update mechanism via Virtual A/B (VABC) slots. It also addresses the practical challenges in custom firmware development due to MediaTek’s SP Flash Tool dependencies and proprietary preloader binaries. 2. Introduction Nokia G21 (TA-1418, TA-1459, TA-1493) is powered by the Unisoc T606 (formerly Spreadtrum) SoC, not MediaTek as often assumed. This distinction critically affects firmware handling: Unisoc uses FDL (Flash Download Loader) and pac package formats rather than MTK’s scatter file. The device ships with Android 11 and is guaranteed upgrades to Android 13. 3. Firmware Partition Scheme Using ls -l /dev/block/by-name/ , the critical partitions are:

from unisoc_pac import PacFile pac = PacFile.read("Nokia_G21_V2.400.pac") boot_partition = pac.get_partition("boot") boot_partition.extract("boot.img") Then using unpack_bootimg.py : nokia g21 firmware

(bootloader) version:0.5 (bootloader) unlocked:no (bootloader) product:atlantic (bootloader) is-userspace:no (bootloader) partition-size:super: 0xE0000000 This is a structured technical paper regarding the

| CVE ID | Component | Fixed in version | |--------|-----------|------------------| | CVE-2024-22014 | wlan_driver heap overflow | V2.400 (April 2024) | | CVE-2023-4886 | bootloader USB descriptor parsing | V2.280 | | CVE-2025-0123 | init selinux bypass in recovery ramdisk | V2.510 (planned) | Introduction Nokia G21 (TA-1418

| Partition | Function | Size (approx) | |-----------|----------|----------------| | proinfo | IMEI, RF calibration | 8 MB | | uboot | U-Boot bootloader | 2 MB | | boot | Kernel + ramdisk | 64 MB | | vbmeta | Verified boot metadata | 8 KB | | super | Dynamic partitions (system, product, vendor) | 3 GB | | userdata | User data & encryption footer | Remainder | | misc | Recovery/boot control flags | 1 MB |