CVE-2026-93202

Overview

The CVE involves a recursive locking bug in the Linux kernel’s I3C subsystem that can cause a deadlock during device registration. The issue occurs when a probe callback re‑acquires a read lock already held by the registration routine, potentially stalling the kernel. This bug affects systems that use the I3C drivers, such as Intel LPSS I3C and the mipi‑i3c‑hci driver.

Description

In the Linux kernel, the following vulnerability has been resolved: i3c: master: Fix recursive locking during device registration i3c_master_register_new_i3c_devs() registers newly discovered devices while holding i3c_bus_normaluse_lock(), a down_read(). device_register() can immediately probe the device, and probe callbacks typically invoke I3C helpers that take i3c_bus_normaluse_lock() again, leading to a recursive acquisition of the same rwsem. rwsems do not support recursive read locking and can deadlock when a writer is waiting. See the "Recursive read locks" section of Documentation/locking/lockdep-design.rst. For example, with Intel LPSS I3C, LOCKDEP generates a WARNING like: # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/unbind # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/bind WARNING: possible recursive locking detected kworker/5:1/94 is trying to acquire lock: ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_device_match_id+0x45/0x370 but task is already holding lock: ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_master_reg_work_fn+0x21/0x5f0 Fix this by separating device creation from device registration. Populate desc->dev under the maintenance lock, collect the devices that still need registration into a local list, then release the lock before calling device_register(). Finally retake the lock and clean up any devices that failed to register. Use the maintenance lock rather than the normal-use lock while adding device objects. A write-side maintenance lock prevents readers from observing a partially initialized desc->dev during initial device population, or desc->dev disappearing if registration fails. The local list requires a list node, so add a list node member to struct i3c_device.

Impact

Availability – the recursive lock can lead to a kernel deadlock, causing a system hang or requiring a reboot. There is no direct impact on confidentiality or integrity, but the resulting downtime can disrupt services and affect uptime.

Remediation

Apply the kernel patch that separates device creation from registration, releasing the normal‑use lock before calling device_register(). Update to the latest kernel release that includes this fix. If immediate patching is not possible, disable the I3C drivers or monitor for lockdep warnings and reboot if a deadlock is detected.

Risk context

Medium severity (CVSS 5.5). The bug can cause a denial‑of‑service via kernel deadlock but does not provide a remote code execution vector. The risk is moderate, especially on systems that actively use I3C devices.

Affected products

• Linux kernel
• Intel LPSS I3C
• mipi-i3c-hci driver
• i3c subsystem