CVE-2025-23147 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
i3c: Add NULL pointer check in i3c_master_queue_ibi()
The I3C master driver may receive an IBI from a target device that has not been probed yet. In such cases, the master calls `i3c_master_queue_ibi()` to queue an IBI work task, leading to "Unable to handle kernel read from unreadable memory" and resulting in a kernel panic.
Typical IBI handling flow: 1. The I3C master scans target devices and probes their respective drivers. 2. The target device driver calls `i3c_device_request_ibi()` to enable IBI and assigns `dev->ibi = ibi`. 3. The I3C master receives an IBI from the target device and calls `i3c_master_queue_ibi()` to queue the target device driver’s IBI handler task.
However, since target device events are asynchronous to the I3C probe sequence, step 3 may occur before step 2, causing `dev->ibi` to be `NULL`, leading to a kernel panic.
Add a NULL pointer check in `i3c_master_queue_ibi()` to prevent accessing an uninitialized `dev->ibi`, ensuring stability.
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Analysis
by VulDB Data Team • 03/15/2026
The vulnerability described in CVE-2025-23147 resides within the Linux kernel's I3C (Improved Inter-Integrated Circuit) master driver implementation, specifically affecting the i3c_master_queue_ibi() function. This issue represents a classic race condition scenario where asynchronous I3C events occur out of sequence with the expected device probing workflow. The I3C protocol is designed for efficient communication between embedded devices, particularly in sensor networks and mobile device ecosystems, making this vulnerability particularly concerning for automotive, IoT, and mobile computing environments where such devices are prevalent. The vulnerability manifests when the master driver attempts to process an Interrupt Block Indicator (IBI) from a target device that has not yet been fully initialized through the standard probing sequence.
The technical flaw occurs due to a missing null pointer validation in the i3c_master_queue_ibi() function, which is responsible for queuing IBI work tasks when the master receives interrupt notifications from target devices. During normal operation, the I3C master driver follows a specific sequence where target devices are first scanned and probed before their respective drivers are loaded and configured to handle IBI events. However, the asynchronous nature of I3C communication means that IBI events can arrive at any time, regardless of whether the target device has completed its initialization process. When an IBI is received before the device driver has called i3c_device_request_ibi() to properly initialize the dev->ibi structure, the function attempts to access a NULL pointer, resulting in an immediate kernel panic and system crash.
The operational impact of this vulnerability extends beyond simple system instability, as it can compromise the reliability of embedded systems that depend heavily on I3C communication protocols. In automotive applications where I3C is used for sensor data collection and vehicle control systems, such a vulnerability could lead to critical system failures during operation. The vulnerability affects systems using Linux kernel versions that include the I3C master driver implementation, particularly those where device drivers may not be fully initialized when IBI events arrive. This issue can be exploited by malicious actors who can potentially trigger IBI events at strategic times to force kernel panics, leading to denial of service conditions that could be particularly problematic in mission-critical applications. The vulnerability aligns with CWE-476 which addresses NULL pointer dereference issues, and represents a specific implementation weakness in the kernel's concurrency handling mechanisms.
The resolution for this vulnerability involves implementing a simple but critical null pointer check within the i3c_master_queue_ibi() function before attempting to access the dev->ibi structure. This mitigation ensures that the driver gracefully handles cases where IBI events arrive before device initialization is complete, preventing the kernel from attempting to access uninitialized memory locations. The fix follows established security practices for preventing null pointer dereferences and aligns with ATT&CK framework techniques related to privilege escalation and system stability compromise. Organizations should prioritize applying this patch to all systems running affected kernel versions, particularly those in critical infrastructure environments where I3C communication is utilized. The vulnerability demonstrates the importance of proper synchronization mechanisms in kernel drivers and highlights the need for comprehensive testing of asynchronous event handling in embedded system components. This fix represents a fundamental defensive programming principle that should be applied across similar driver implementations to prevent similar race condition vulnerabilities from manifesting in other kernel subsystems.