CVE-2026-64016: ksmbd: fix durable reconnect error path file lifetime

From: Greg Kroah-Hartman <[email protected]>

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

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

ksmbd: fix durable reconnect error path file lifetime

After a durable reconnect succeeds, ksmbd_reopen_durable_fd() republishes
the same ksmbd_file into the session volatile-id table. If smb2_open()
then takes a later error path, cleanup first calls ksmbd_fd_put(work, fp)
and then unconditionally calls ksmbd_put_durable_fd(dh_info.fp).

In this case fp and dh_info.fp are the same object. The first put drops the
reconnect lookup reference, but the final durable put can run
__ksmbd_close_fd(NULL, fp). Because the final close is not session-aware,
it can free the file object without removing the volatile-id entry that was
just published into the session table.

Use the session-aware put for the final reconnect drop when the reconnect
had already succeeded and the error path is cleaning up the republished
file. Earlier reconnect failures, before fp is assigned to dh_info.fp, keep
using the durable-only put path.

The Linux kernel CVE team has assigned CVE-2026-64016 to this issue.


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

	Issue introduced in 6.18.33 with commit ce2e164c1c51c3f7813b80f8c926836e896bcbb3 and fixed in 6.18.34 with commit a1a39f227c80cbf369767badc32cba2b225147d1
	Issue introduced in 7.0.10 with commit 97a0cd55283b4e63fd92804da91c8d9896adcad9 and fixed in 7.0.11 with commit 6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3

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-2026-64016
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/smb2pdu.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/a1a39f227c80cbf369767badc32cba2b225147d1
	https://git.kernel.org/stable/c/6cb0b9385320110fe24a5d5ac0000ade4bb3a3f3
	https://git.kernel.org/stable/c/3515503322f4819277091839eed46b695096aca5