Linux LTS kernel updates fix Thunderbolt stack overflows and USB ghost devices
The latest Linux LTS kernel updates for 6.12.93 and 6.18.35 drop a heavy batch of patches that target real hardware pain points rather than theoretical edge cases. These releases clean up memory corruption in Thunderbolt drivers, fix ghost USB devices that refuse to vanish, and repair serial console lockups on legacy DEC hardware. Readers running these stable branches will notice fewer unexpected disconnects and tighter control over power management on modern Intel and ARM platforms.
Thunderbolt recursion limits and USB ghost device cleanup
Users who plug and unplug Thunderbolt docks while running heavy I/O will notice fewer kernel panics now, since the recursion cap stops the parser from eating the stack. A crafted peer that chains directory entries into a back-reference loop used to drive the parser straight into a kernel stack exhaustion. The new code rejects blocks exceeding a depth of eight, which covers every legitimate XDomain layout while keeping untrusted docks from crashing the system.
The USB subsystem updates tackle the stubborn ghost device problem on Tegra dual-role ports. When a gadget unplugs, the old path cleared port power directly and skipped the normal xHCI disconnect processing. The controller never generated the port change status, so the USB core kept the device listed in the internal tree. The old power clearing logic was pointless bloat that broke standard disconnect handling. The new path uses an otg_set_port_power flag to handle the disconnect naturally on newer SoCs while keeping explicit power management where the hardware actually needs it.
Serial port SysRq handling and DECstation console recovery
The 8250 and 8250_dw serial drivers had a frustrating regression where SysRq break characters got swallowed silently. The interrupt handler captured the magic key but used a plain lock guard that dropped the character before the console could dispatch it. Switching to the sysrq-aware unlock helper restores the ability to trigger emergency commands without losing the input. Legacy DECstation users also get relief from a bootconsole handover lockup. The zs and dz serial drivers were resetting line parameters and disabling transmitters too early, which froze the firmware console handler. The patches adjust the reset sequence to match the expected 9600n8 setup and force a proper channel reset instead of a hardware reset that interfered with the other port.
MPTCP window accounting and Intel CPU frequency scaling
Multipath TCP handling saw several memory and state accounting patches that prevent data loss during fallback scenarios. The receive window tracking now resets properly on disconnect, and the code borrows forward memory from subflow sockets instead of releasing and reallocating it immediately. This reduces fragmentation failures when backing up traffic across multiple interfaces. Intel platform drivers get a scaling factor correction for Raptor Lake-E processors. The chip shares an ID with Raptor Lake-S but lacks E-cores, which caused the hybrid scaling lookup to return the wrong multiplier. The fix forces the P-core scaling path for all non-E-cores, restoring accurate frequency mapping for workloads that rely on Intel pstate.
Memory management, GPU power states, and ARM KVM stability
The slub memory allocator picks up a lock ordering fix that prevents deadlocks when flushing RCU sheaves during cache destruction. Kernel developers who hit slab corruption during heavy memory allocation will find the cpus_read_lock placement stabilizes their teardown paths. Intel graphics drivers fix a DC6 power well mismatch warning that appeared when panel self-refresh tracked vblank enable states incorrectly. Storing the last notification status prevents duplicate wake references from triggering false power state mismatches. ARM KVM patches address nested MMU array reallocation and translation cache reference counting. The nested stage two MMU structures now copy entries under the correct lock, and the ITS cache invalidation drops references only for actually erased entries, stopping double-free crashes in virtualized interrupt routing.
Linux kernel 6.12.93 released
Linux kernel version 6.12.93 is now available:
Full source: https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.12.93.tar.xz
Patch: https://cdn.kernel.org/pub/linux/kernel/v6.x/patch-6.12.93.xz
PGP Signature: https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.12.93.tar.sign
You can view the summary of the changes at the following URL:
https://git.kernel.org/stable/ds/v6.12.93/v6.12.92
Linux kernel 6.18.35 released
Linux kernel version 6.18.35 is now available:
Full source: https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.35.tar.xz
Patch: https://cdn.kernel.org/pub/linux/kernel/v6.x/patch-6.18.35.xz
PGP Signature: https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.35.tar.sign
You can view the summary of the changes at the following URL:
https://git.kernel.org/stable/ds/v6.18.35/v6.18.34
Keep an eye on your system logs after applying these patches. The Thunderbolt and USB changes tend to smooth out the most annoying hotplug gremlins, while the serial and power management fixes mainly help stability on older or heavily loaded hardware. Reboot when convenient and let the stable branches do their work.
