SB20260917125 - NULL pointer dereference in Linux kernel f2fs

Description

This security bulletin contains information about 1 vulnerability.

1) NULL pointer dereference (CVE-ID: CVE-2026-89835)

CWE-ID: CWE-476 - NULL Pointer Dereference

CVSSv4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a null pointer dereference in the f2fs ckpt_thread_ioprio sysfs store path when writing the checkpoint thread I/O priority through sysfs while checkpoint merge is enabled and no checkpoint thread is running. A local user can write a checkpoint thread I/O priority value through sysfs to cause a denial of service.

A read-only mount is one condition in which no checkpoint merge thread is started.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/5cb33b00c8fbb6e8f1fa3d281c3036d5f7c7c41f
• https://git.kernel.org/stable/c/8f3b99c50dd0da1777994ce7c7e60d39b9f60f4b
• https://git.kernel.org/stable/c/a6573f3ffc19542de9ebc1a2b1f930fd48ba538c
• https://git.kernel.org/stable/c/aefcec3bebdeed2bff444378122300763325ba23