CVE-2022-49162 is a vulnerability identified in the Linux kernel's framebuffer device driver for the sm712fb hardware. The issue arises specifically in the smtcfb_write() function, which handles writing data to the framebuffer. When the driver attempts to write exactly three bytes to the framebuffer, it triggers a crash due to an unhandled page fault at an invalid memory address (ffffc90001ffffff). The crash occurs because of a flaw in the driver's handling of endianness fixup code, which was implemented in an open-coded manner and led to improper memory access. This vulnerability results in a denial-of-service (DoS) condition by causing the kernel to crash when the faulty write operation is performed. The root cause was addressed by removing the problematic endianness fixup code, thereby preventing the crash. The vulnerability affects specific Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2. There are no known exploits in the wild, and no CVSS score has been assigned yet. The vulnerability requires the ability to write to the framebuffer device, which typically implies local access or privileges to interact with the device node. The impact is primarily on system stability and availability rather than confidentiality or integrity.

For European organizations, the primary impact of CVE-2022-49162 is the potential for denial-of-service conditions on Linux systems utilizing the sm712fb framebuffer driver. This could lead to unexpected kernel crashes, resulting in system downtime, loss of productivity, and potential disruption of critical services, especially in environments where Linux is used for embedded systems, industrial control, or specialized hardware relying on this framebuffer driver. Although the vulnerability does not appear to allow privilege escalation or data compromise, the availability impact can be significant in operational technology (OT) environments or servers where uptime is critical. Organizations running Linux distributions with this vulnerable driver version should be aware that attackers or even inadvertent local users could trigger a system crash by writing three bytes to the framebuffer device. This could be exploited in multi-user systems or shared environments. The lack of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to maintain system reliability.

1. Apply the patch or update the Linux kernel to a version where the sm712fb driver has been fixed, removing the open-coded endianness fixup code causing the crash. 2. If patching is not immediately possible, restrict access to the framebuffer device nodes (e.g., /dev/fb*) by tightening permissions to prevent unprivileged users from writing to the device. 3. Monitor system logs for any unusual framebuffer write attempts or kernel oops messages that could indicate exploitation attempts. 4. In environments using custom or embedded Linux kernels, ensure that the sm712fb driver source is updated and rebuilt with the fix applied. 5. Conduct regular kernel updates and vulnerability scanning to detect and remediate similar issues promptly. 6. For critical systems, consider implementing kernel crash dump analysis and automated recovery mechanisms to minimize downtime in case of crashes.