CVE-2024-26958: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-26958 is a use-after-free (UAF) vulnerability discovered in the Linux kernel's NFS direct writes functionality. The vulnerability was discovered in early 2024 and affects multiple versions of the Linux kernel up to versions 5.10.215, 5.15.154, 6.1.84, 6.6.24, 6.7.12, and 6.8.3. The issue occurs in the fs/nfs/direct.c component (NVD).

The vulnerability stems from a race condition in the NFS direct write implementation where asynchronous commit requests can complete before subsequent requests are submitted, leading to a double completion of the nfsdirectrequest. This results in a use-after-free condition, manifesting as a refcount underflow warning. The issue has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can lead to a use-after-free condition in the Linux kernel's NFS implementation, potentially resulting in system crashes or memory corruption. In production environments, the issue manifests consistently, with warning messages appearing approximately every 10 minutes during heavy NFS operations (Kernel Patch).

The issue has been fixed by implementing proper commit request handling using the nfscommitbegin/nfscommitend pattern, similar to other completion handling in the NFS code. The fix has been confirmed effective through stress testing, with no recurrence of the warning messages after application (Kernel Patch).