Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-08-15T00:00:00 kernel: ocfs2: fix NULL h_transaction deref in ocfs2_assure_trans_credits 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-476

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix NULL h_transaction deref in ocfs2_assure_trans_credits [BUG] A direct write over unwritten extents can panic the kernel in ocfs2_assure_trans_credits() when the journal aborts during DIO completion. The crash is a general protection fault from a NULL pointer dereference. [CAUSE] ocfs2_dio_end_io_write() loops over a direct write's unwritten extents, marking each written under a single journal handle. If the journal aborts (for example after an I/O error) while the extent tree is being updated, the handle is left aborted with its transaction pointer cleared. The extent merge treats that failure as not critical and reports success, so the loop keeps using the handle. ocfs2_assure_trans_credits() reads the handle's remaining credits without first checking whether the handle is aborted, and that read dereferences the cleared transaction pointer. [FIX] A journal abort is recorded in the handle itself, so callers are expected to test the handle rather than rely on a returned error. Make ocfs2_assure_trans_credits() do that, as the other ocfs2 journal helpers already do, and return -EROFS when the handle is aborted.

A flaw was found in the Linux kernel's OCFS2 component. A local user with write access to an OCFS2 filesystem could trigger a kernel panic by performing a direct write over unwritten extents. This occurs when the journal aborts during Direct I/O (DIO) completion, leading to a NULL pointer dereference in the `ocfs2_assure_trans_credits` function. Successful exploitation results in a system crash, causing a Denial of Service (DoS).

Red Hat Enterprise Linux 10 Not affected kernel Red Hat Enterprise Linux 6 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel Red Hat Enterprise Linux 7 Not affected kernel-rt Red Hat Enterprise Linux 8 Not affected kernel Red Hat Enterprise Linux 8 Not affected kernel-rt Red Hat Enterprise Linux 9 Not affected kernel Red Hat Enterprise Linux 9 Not affected kernel-rt https://www.cve.org/CVERecord?id=CVE-2026-72163 https://nvd.nist.gov/vuln/detail/CVE-2026-72163 https://lore.kernel.org/linux-cve-announce/2026081536-CVE-2026-72163-a2e8@gregkh/T