It’s a shocking point of no return
With Android 13 out of Google’s hands and on developers tweaking the OS for their own ends, the road will be tricky. There are a number of new features that the bump release brings that need to be tested but before they can do that they will need to make sure of one crucial thing and that is to install Android 13 on both system partitions of their Pixel device. A developer has discovered what happens when things go wrong without this updated second score.
There are two concepts in Android at play here that explain what happened: seamless updates and bootloader rollback protection.
The idea of A/B system partitions was first introduced with Android 7.1 Nougat in 2016 to allow software updates to be installed seamlessly on a partition while still allowing the device to be used with its software. current on the other partition. Once the installation is complete, the user will then be able to immediately reboot to the updated partition, saving them considerable downtime while waiting for the software to install during the reboot process. It also leaves the other partition with the old software version.
Going to the idea of rollback protection, sometimes Google updates a device’s bootloader to prevent an older version of Android from loading on a device – this is usually in response to known vulnerabilities. Indeed, with the Android 13 update for the Pixel 6, Pixel 6 Pro, and Pixel 6a devices, Google had indeed ensured that these phones would not boot if an Android 12 version were later installed on them.
A developer fell victim to a collision of these concepts. They were working with an Android Open Source Project build of Android 13 on their Pixel 6 when the device failed to boot.
It wouldn’t have been such a catastrophic failure in most cases, because the phone could immediately turn to its working partition B and boot from there. But since partition B was still on Android 12, the restore protection function kicked in and prevented the device from turning on. And with no known way to go back and attempt another boot from the Android 13 partition, this Pixel is as good as bricked up.
Who is most likely to encounter this type of scenario? We suspect it will be developers pulling ADB or fastboot commands that could cause a sixth-gen Pixel running Android 13 to crash and fail — @flawedworlddev notes that the anti-rollback feature only kicks in after a first boot managed on Android 13 to boot from its A partition. We’d also say there’s a non-zero chance that consumers are vulnerable to this problem right now because some sort of app crash or system failure could trigger a boot failure, but the odds are extremely low and will go away completely if they are. managed to load a future software update.
But once the phone is gone, it’s gone. Developers should ensure that both partitions of their Pixel devices get successful Android 13 installs before playing with anything else.