CVE-2024-49956: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-49956 affects the Linux kernel's GFS2 (Global File System 2) implementation. The vulnerability was discovered in the gfs2fillsuper() function where a double destroyworkqueue error occurs. When gfs2fillsuper() fails, destroyworkqueue() is called within gfs2glhashclear(), and the subsequent code path calls destroyworkqueue() on the same work queue again (Kernel Git). The vulnerability affects Linux kernel versions from 6.11 up to (excluding) 6.11.3 (NVD).

The vulnerability is classified as a NULL Pointer Dereference (CWE-476) with a CVSS v3.1 base score of 5.5 (Medium), and vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. The issue stems from improper handling of work queue destruction in the GFS2 filesystem code. The bug was introduced in commit 30e388d57367 which implemented 'Switch to a per-filesystem glock workqueue' (Kernel Git).

The vulnerability can lead to a system crash (denial of service) when the GFS2 filesystem mount operation fails, due to the double destruction of the same work queue (NVD).

The issue has been fixed by setting the work queue pointer to NULL after the first destroy_workqueue() call and checking for a NULL pointer before attempting to destroy the work queue again. The fix has been implemented in the Linux kernel version 6.11.3 and later (Kernel Git).