SB20260917124 - Out-of-bounds write in Linux kernel f2fs

Description

This security bulletin contains information about 1 vulnerability.

1) Out-of-bounds write (CVE-ID: CVE-2026-89834)

CWE-ID: CWE-787 - Out-of-bounds write

CVSSv4: 0 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to perform out-of-bounds I/O.

The vulnerability exists due to incomplete iteration over active curseg types in free_segment_range() when shrinking an F2FS filesystem. A local user can initiate a filesystem shrink operation while active in-memory curseg types reside in the target range to perform out-of-bounds I/O.

Non-persistent in-memory curseg types, including CURSEG_COLD_DATA_PINNED and CURSEG_ALL_DATA_ATGC, can remain in the truncated range.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/3b85edf3391f3e1f624f409a7d2d239885f567b7
• https://git.kernel.org/stable/c/8ec06f50ddd8d201bd7e55b896ae28ed9d4cb7d1
• https://git.kernel.org/stable/c/b8ae1228c153622afa71a179c9d4dc268117e0f0
• https://git.kernel.org/stable/c/b9776094aa7118e8e5dfdcd791ffc8330c5ca408