CVE-2026-68381: ksmbd: pin conn during async oplock break notification

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: pin conn during async oplock break notification

smb2_oplock_break_noti() and smb2_lease_break_noti() store a ksmbd_conn
pointer in an async ksmbd_work and then queue that work on ksmbd-io.  The
work only increments conn->r_count, which prevents teardown from passing
the pending-request wait after the increment, but it does not pin the
struct ksmbd_conn object.

If connection teardown races with an oplock break notification, the last
conn reference can be dropped before the queued worker finishes.  The
worker then uses the freed conn in ksmbd_conn_write() and
ksmbd_conn_r_count_dec().

Take a real conn reference when publishing the conn pointer to the async
work item, and drop it after the notification work has decremented
r_count.  Apply the same lifetime rule to lease break notification, which
uses the same work->conn pattern.

The Linux kernel CVE team has assigned CVE-2026-68381 to this issue.


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

	Issue introduced in 6.6.84 with commit 09aeab68033161cb54f194da93e51a11aee6144b and fixed in 6.6.148 with commit 0f72fc9659d7f585460d43c158055df5afdcffb6
	Issue introduced in 6.12.20 with commit a4261bbc33fbf99b99c80aa3a2c5097611802980 and fixed in 6.12.101 with commit 793e1c7041b93af96ff87e678329bc16aee7ba88
	Issue introduced in 6.14 with commit 3aa660c059240e0c795217182cf7df32909dd917 and fixed in 6.18.42 with commit 6ecb252efa0b413ac3d9979fb4eec247f8fc1258
	Issue introduced in 6.14 with commit 3aa660c059240e0c795217182cf7df32909dd917 and fixed in 7.1.6 with commit 14062c74e5b25c27edcff7a2fe0dc701c930b372
	Issue introduced in 6.14 with commit 3aa660c059240e0c795217182cf7df32909dd917 and fixed in 7.2-rc4 with commit aa5d8f3f96aa11a4a54ce993c11ce8af11c546f9
	Issue introduced in 6.13.8 with commit f17d1c63a76b0fe8e9c78023a86507a3a6d62cfa

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-2026-68381
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/smb/server/oplock.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/0f72fc9659d7f585460d43c158055df5afdcffb6
	https://git.kernel.org/stable/c/793e1c7041b93af96ff87e678329bc16aee7ba88
	https://git.kernel.org/stable/c/6ecb252efa0b413ac3d9979fb4eec247f8fc1258
	https://git.kernel.org/stable/c/14062c74e5b25c27edcff7a2fe0dc701c930b372
	https://git.kernel.org/stable/c/aa5d8f3f96aa11a4a54ce993c11ce8af11c546f9