Unplugging Logitech USB Receivers Has Been Causing The Linux Kernel To Crash

Queued up this week as part of the HID subsystem fixes ahead of today's Linux 6.6-rc6 kernel test release has been a rather embarrassing bug: unplugging Logitech USB receivers has for the past several months been causing the Linux kernel to crash. After a number of bug reports around this issue from unplugging Logitech keyboard/mice receivers to simply switching away on a USB switch with the device(s) attached, the Linux 6.6-rc6 kernel is carrying the fix and it's also marked for back-porting to existing stable Linux kernel series.

Red Hat's Hans de Goede continues to do wonders for fixing up and improving Linux desktop/laptop hardware support. He took on to dealing with this Logitech USB receiver disconnect bug. That followed a number of different Red Hat bug reports over the summer: USB disconnect causes kernel crash, power_supply_uevent on USB leads to page_fault_oops, kernel module hid_logitech_dj causes crash and broken USB, and Logitech unify receiver not working properly, among others.

As explained in the patch fixing the kernel crash on receiver USB disconnect, there are four time-of-check vs. time-of-use races that needed to be addressed.

The fix was merged as part of this week's HID fixes for Linux 6.6-rc6 and in turn will be back-ported to the Linux stable series over the coming days. In the meantime, don't unplug your Logitech USB receiver if you are on a recent Linux kernel version to avoid the possible kernel crash.