CVE-2023-54068: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-54068 is a kernel bug in the Linux kernel's f2fs (Flash-Friendly File System) compress subsystem, specifically in the f2fs_write_raw_pages() function. The vulnerability involves a missing call to f2fs_wait_on_page_writeback(), which can trigger a BUG_ON() (kernel panic) when files are written concurrently, causing the same page to be marked for writeback multiple times. It affects the Linux kernel and was published on December 24, 2025. The EPSS score is approximately 0.024% (very low), and no CVSS score has been formally assigned in available sources (Feedly, CVE.org).

The root cause is a race condition (CWE-362) in the f2fs compress path within f2fs_write_raw_pages(). When multiple processes concurrently write to the same file, Process A may redirty and unlock a page, Process B then sets it to writeback state, and Process C triggers a new write cycle — causing Process A to attempt a second set_page_writeback() on the same page. This double-writeback triggers the BUG() assertion in folio_end_writeback() at mm/filemap.c:1619. The fix requires calling f2fs_wait_on_page_writeback() before proceeding with the write in f2fs_write_raw_pages() to ensure the page is no longer in writeback state before re-marking it (Feedly).

Successful triggering of this vulnerability causes a kernel BUG() panic, resulting in a system crash and complete loss of availability for the affected host. The impact is limited to availability (denial of service); there is no evidence of confidentiality or integrity compromise. The vulnerability requires local access and concurrent file write operations on an f2fs-mounted filesystem with compression enabled (Feedly, CVE.org).

There is no known public exploit code, no evidence of in-the-wild exploitation, and this vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS score is 0.024%, reflecting a very low probability of exploitation. Triggering the bug requires local access to a system with an f2fs filesystem using compression, and the ability to perform concurrent file write operations (Feedly).

The Linux kernel maintainers have released patches addressing this issue across multiple stable branches, with fixes available at the following kernel.org commits: 6604df2a9d07, 169134da419c, 9940877c4fe7, a8226a45b2a9, and ad31eed06c3b. Users should update to a patched kernel version that includes these fixes. As a workaround, avoiding the use of f2fs compression on affected systems can prevent the race condition from being triggered. Distributions such as Alibaba Cloud Linux (alinux3-sa-20260139) and others have begun incorporating these fixes into their kernel packages (Feedly, CVE.org).