CVE-2022-49308 is a vulnerability identified in the Linux kernel's extcon (external connector) subsystem. The issue arises because the extcon device is created before the driver data is properly set via dev_set_drvdata(). This timing flaw allows an attacker or any user-space process to invoke sysfs interfaces such as state_show() intermittently before the driver data pointer (edev) is initialized. When this occurs, the kernel attempts to dereference a null pointer, leading to a kernel Oops (a kernel crash or panic). The backtrace provided shows the sequence of kernel functions leading to the fault, starting from state_show() through various sysfs and virtual file system read operations. The root cause is a race condition in the driver registration sequence, where the extcon device is exposed to sysfs before its internal driver data is ready. The fix involves modifying the driver registration process to ensure that the driver data is set before the extcon device is created and exposed. This vulnerability does not appear to have any known exploits in the wild and does not have an assigned CVSS score. However, it can cause denial of service due to kernel crashes if exploited.

For European organizations, this vulnerability primarily poses a risk of denial of service (DoS) on Linux systems that utilize the extcon subsystem, which is common in embedded devices, mobile platforms, and some server environments. A kernel Oops can cause system instability, crashes, or reboots, potentially disrupting critical services or operations. While this vulnerability does not directly lead to privilege escalation or remote code execution, the resulting system crashes can impact availability and reliability. Organizations relying on Linux-based infrastructure, especially those using custom or embedded Linux kernels with extcon support, may experience service interruptions. In sectors such as telecommunications, manufacturing, or IoT deployments prevalent in Europe, this could affect operational technology systems. Additionally, the vulnerability could be exploited by local users or processes with access to sysfs interfaces to trigger kernel crashes, which may be leveraged as part of a broader attack to degrade system availability.

To mitigate this vulnerability, European organizations should: 1) Apply the official Linux kernel patches that reorder the driver registration to set driver data before creating the extcon device. Monitoring Linux kernel updates and promptly deploying security patches is critical. 2) For embedded or custom Linux distributions, ensure that kernel builds incorporate this fix and validate the extcon driver initialization sequence. 3) Restrict access to sysfs interfaces related to extcon devices by enforcing strict permissions and limiting user-space access to trusted users and processes only. 4) Implement kernel crash monitoring and alerting to detect and respond quickly to Oops events. 5) Where feasible, isolate critical systems from untrusted users or processes that could trigger the vulnerability. 6) Conduct thorough testing after patching to confirm system stability and that the vulnerability is resolved. These steps go beyond generic advice by focusing on controlling sysfs access and ensuring embedded systems are updated, which are often overlooked in standard patching procedures.