CVE-2026-72163: ocfs2: fix NULL h_transaction deref in ocfs2_assure_trans_credits

CVE-2026-72163: ocfs2: fix NULL h_transaction deref in ocfs2_assure_trans_credits

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-72163 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.10.221 with commit a68b896aa56e435506453ec8835bc991ec3ae687 and fixed in 5.10.261 with commit 2d80e9c56718435a9c9f5f24dbc954989aead579
	Issue introduced in 5.15.162 with commit 320273b5649bbcee87f9e65343077189699d2a7a and fixed in 5.15.212 with commit 942b818b396c24c452681803ff291552317d2ef1
	Issue introduced in 6.1.97 with commit 9ea2d1c6789722d58ec191f14f9a02518d55b6b4 and fixed in 6.1.178 with commit 7146d191dae3a8efdb957993fb61a55713186266
	Issue introduced in 6.6.37 with commit c05ffb693bfb42a48ef3ee88a55b57392984e111 and fixed in 6.6.145 with commit f14aaaa130356ee4adb44de947c098637c70df8f
	Issue introduced in 6.10 with commit be346c1a6eeb49d8fda827d2a9522124c2f72f36 and fixed in 6.12.97 with commit 6ad7532a23bc94076efe9f1486dd7f7493c090ff
	Issue introduced in 6.10 with commit be346c1a6eeb49d8fda827d2a9522124c2f72f36 and fixed in 6.18.40 with commit bd73971fad89d5ee4ea0ba9b92d2ea08733c4a64
	Issue introduced in 6.10 with commit be346c1a6eeb49d8fda827d2a9522124c2f72f36 and fixed in 7.1.5 with commit 253ed993e0b36997ec7b04c1ff76103b38241de2
	Issue introduced in 6.10 with commit be346c1a6eeb49d8fda827d2a9522124c2f72f36 and fixed in 7.2-rc1 with commit f9ab30c96b0f00c20c6dac93681bdae3a033d229
	Issue introduced in 6.9.8 with commit 331d1079d58206ff7dc5518185f800b412f89bc6

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-72163
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/ocfs2/journal.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/2d80e9c56718435a9c9f5f24dbc954989aead579
	https://git.kernel.org/stable/c/942b818b396c24c452681803ff291552317d2ef1
	https://git.kernel.org/stable/c/7146d191dae3a8efdb957993fb61a55713186266
	https://git.kernel.org/stable/c/f14aaaa130356ee4adb44de947c098637c70df8f
	https://git.kernel.org/stable/c/6ad7532a23bc94076efe9f1486dd7f7493c090ff
	https://git.kernel.org/stable/c/bd73971fad89d5ee4ea0ba9b92d2ea08733c4a64
	https://git.kernel.org/stable/c/253ed993e0b36997ec7b04c1ff76103b38241de2
	https://git.kernel.org/stable/c/f9ab30c96b0f00c20c6dac93681bdae3a033d229