CVE-2024-49924 is a use-after-free (UAF) vulnerability identified in the Linux kernel's framebuffer device driver for the PXAFB (PowerXcel framebuffer) subsystem. The vulnerability arises during the removal of the PXAFB kernel module, specifically within the cleanup sequence handled by the pxafb_remove function. The issue stems from a race condition between the freeing of framebuffer information structures and scheduled work that still references these freed structures. In detail, the pxafb_probe function initializes framebuffer info structures and associates a task (pxafb_task) with them. The pxafb_blank function, part of the framebuffer operations, can schedule work that accesses the framebuffer info. When the module is removed, pxafb_remove calls unregister_framebuffer, which in turn calls do_unregister_framebuffer and put_fb_info to free the framebuffer info structure (fbi->fb). However, if the scheduled work is not canceled before this cleanup, it may attempt to access the freed framebuffer info, leading to a use-after-free condition. This can cause kernel memory corruption, potentially leading to system crashes or privilege escalation. The vulnerability is mitigated by ensuring that any scheduled work is canceled before the framebuffer info is freed during module removal. Notably, exploitation requires root privileges to remove the driver at runtime, limiting the attack surface to privileged users. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-49924 is primarily relevant to environments running Linux kernels with the PXAFB framebuffer driver enabled and where kernel modules can be dynamically removed by privileged users. The vulnerability could allow a local attacker with root privileges to cause a kernel crash or potentially execute arbitrary code in kernel space by exploiting the use-after-free condition. This could lead to denial of service or privilege escalation scenarios, compromising system integrity and availability. While the requirement for root access limits remote exploitation, insider threats or compromised administrative accounts could leverage this vulnerability to deepen system compromise. Organizations relying on embedded Linux systems or specialized hardware using PXAFB (common in certain industrial or embedded applications) may be particularly at risk. The vulnerability does not directly expose confidentiality risks but could indirectly affect data integrity and system availability. Given the widespread use of Linux in European IT infrastructure, especially in servers, cloud environments, and embedded devices, awareness and patching are important to maintain operational security.

1. Apply the official Linux kernel patch that cancels scheduled work before freeing framebuffer info during module removal, as indicated in the vulnerability fix. 2. Restrict root access and enforce strict privilege management to prevent unauthorized module removal or kernel manipulation. 3. Monitor and audit kernel module loading and unloading activities to detect suspicious behavior indicative of exploitation attempts. 4. For embedded or specialized systems using PXAFB, verify kernel versions and update to patched releases promptly. 5. Employ kernel hardening techniques such as Kernel Page Table Isolation (KPTI) and address space layout randomization (ASLR) to reduce exploitation likelihood. 6. In environments where dynamic module removal is unnecessary, consider disabling module unloading to reduce attack surface. 7. Conduct regular vulnerability assessments and penetration testing focusing on kernel-level vulnerabilities and privilege escalation paths.