CVE-2024-42254 is a vulnerability identified in the Linux kernel's io_uring subsystem, specifically related to error handling inconsistencies in the function io_alloc_pbuf_ring(). The issue arises from a NULL pointer dereference due to inconsistent checks between NULL and IS_ERR error handling mechanisms. This flaw was detected by Syzkaller (Syz), a kernel fuzzing tool, and manifests as a kernel address sanitizer (KASAN) null-pointer dereference within a small memory range near address zero. The vulnerable code path involves the removal and destruction of io_uring buffers, particularly in the functions __io_remove_buffers, io_put_bl, io_destroy_buffers, io_ring_ctx_free, and io_ring_exit_work, which are part of the io_uring kernel buffer management. The null pointer dereference can cause a kernel panic or system crash, leading to denial of service (DoS). The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is present in recent kernel builds prior to the patch. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability does not require user interaction but may require local access or privileges to trigger, depending on the system configuration and usage of io_uring interfaces. Io_uring is a high-performance asynchronous I/O interface used increasingly in modern Linux applications and services, making this vulnerability relevant for systems relying on it for efficient I/O operations.

For European organizations, the impact of CVE-2024-42254 primarily involves potential denial of service conditions on Linux systems utilizing io_uring. This could disrupt critical services, especially in environments running high-performance servers, cloud infrastructure, or containerized workloads that leverage io_uring for asynchronous I/O. The kernel panic or crash could lead to downtime, impacting availability and operational continuity. While this vulnerability does not directly expose confidentiality or integrity risks, the resulting service interruptions could affect business operations, particularly in sectors like finance, telecommunications, and public services where Linux servers are prevalent. Additionally, if exploited in multi-tenant environments such as cloud providers or hosting services, it could impact multiple customers. The lack of known exploits reduces immediate risk, but the presence of a kernel-level bug in a widely used subsystem necessitates prompt attention to avoid future exploitation attempts.

To mitigate CVE-2024-42254, European organizations should: 1) Apply the latest Linux kernel patches as soon as they become available from trusted sources or distributions, ensuring the fix for io_uring error handling is included. 2) Monitor kernel updates from major Linux distributions (e.g., Debian, Ubuntu, Red Hat, SUSE) and prioritize patching in production and development environments. 3) Restrict access to io_uring interfaces where possible, limiting usage to trusted applications and users to reduce the attack surface. 4) Implement kernel hardening techniques such as enabling Kernel Address Sanitizer (KASAN) in testing environments to detect similar issues proactively. 5) Employ robust system monitoring and alerting to detect abnormal kernel crashes or reboots that may indicate exploitation attempts. 6) For cloud and hosting providers, isolate workloads and enforce strict privilege separation to minimize impact scope. 7) Review and update incident response plans to include kernel-level vulnerabilities and potential denial of service scenarios related to io_uring.