systemd service which disables reset mitigation upon shutdown
** Attachment added: "disable-reset-attack-mitigation.service"
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1871395/+attachment/5348751/+files/disable-reset-attack-mitigation.service
** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/1871395
Title:
CONFIG_RESET_ATTACK_MITIGATION should not be enabled by default
without additional scripts
Status in linux package in Ubuntu:
Confirmed
Bug description:
Description of problem:
Ubuntu 19.10 kernel 5.3.0-46-generic has Reset Attack Mitigation enabled
(CONFIG_RESET_ATTACK_MITIGATION) which may cause strange reboot sequence on
certain hardware (Lenovo Thinkpad X220).
Instead of rebooting normally, the laptop would hard power off (without
properly stopping peripherals and internal devices, which may be spotted by HDD
losing power with a specific unusual sound) and then powers on again after 1
second.
This kernel configuration option should not be enabled unless additional
scripts, which disable RAM clean step upon normal poweroff/reboot. I made the
systemd service to workaround the problem, which writes "0" to
MemoryOverwriteRequestControl EFI variable:
https://gist.github.com/ValdikSS/86352b03ec3ed3c8713b78c7e20dc222
The author of this kernel option, Matthew Garett, wrote the following:
>if userspace can ensure that all secrets are
>removed as part of a controlled shutdown, it can reset this variable to
>0 before triggering a hardware reboot.
https://lwn.net/Articles/730006/
Version-Release number of selected component (if applicable):
linux-image 5.3.0-46-generic
How reproducible:
Always
Steps to Reproduce:
1. Boot Ubuntu 19.10, either live or installed
2. Reboot the computer (Lenovo X220 laptop in my case)
Actual results:
The computer perform hard power off and power on after 1 second
Expected results:
The computer reboots without losing power
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