CVE-2026-74629: net/dibs: Correct freeing of dmb_clientid_arr

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

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

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

net/dibs: Correct freeing of dmb_clientid_arr

A dibs device interrupt handler can be active after dibs_dev_del() and
may still access dmb_clientid_arr. (UAF)

In case of a failure in dibs_dev_add() being called by dibs_lo_dev_probe()
dmb_clientid_arr is freed twice (double free).

Free dmb_clientid_arr in dibs_dev_release() after last reference is gone.
Note that allocating in dibs_dev_add() instead of dibs_dev_alloc() is ok
for now, because no dmbs can be registered before dibs_dev_add().

The Linux kernel CVE team has assigned CVE-2026-74629 to this issue.


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

	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 6.18.45 with commit ece6426b61241e9bfb41aa131f235168f55229b1
	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 7.1.9 with commit 7a1df20a8d2cc89e3a442b6e0b43b1cacde8d403
	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 7.2 with commit 9e6869be49064915edb6c8776b27c376cfdb0df5

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-2026-74629
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:
	drivers/dibs/dibs_loopback.c
	drivers/dibs/dibs_main.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/ece6426b61241e9bfb41aa131f235168f55229b1
	https://git.kernel.org/stable/c/7a1df20a8d2cc89e3a442b6e0b43b1cacde8d403
	https://git.kernel.org/stable/c/9e6869be49064915edb6c8776b27c376cfdb0df5