CVE-2026-74617: dibs: initialise dibs->lock in dibs_dev_alloc()

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

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

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

dibs: initialise dibs->lock in dibs_dev_alloc()

dibs->lock is initialised by dibs_dev_add(), but a dibs device can
already take interrupts before that call: ism_probe() runs
ism_dev_init(), and hence request_irq(), before it calls
dibs_dev_add(). No client can have registered a dmb at that point, so
no dmb interrupt can occur, but a GID event interrupt can, and
ism_handle_irq() takes dibs->lock unconditionally on entry, before it
inspects anything else.

Initialise the lock in dibs_dev_alloc() instead, so that it is valid as
soon as a driver can publish the device to its interrupt handler.

The Linux kernel CVE team has assigned CVE-2026-74617 to this issue.


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

	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 6.18.45 with commit fe79571f40434b257d68cbfb7b3ae93a794d8a11
	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 7.1.9 with commit 2926031acba100d0c18fcfaa7a2ed29609318848
	Issue introduced in 6.18 with commit cc21191b584c6f7836b0f10774f8278b7cbfba10 and fixed in 7.2 with commit c27e360545373b7aee9862a5beef3b9fb3df0c25

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-2026-74617
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_main.c
	include/linux/dibs.h


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/fe79571f40434b257d68cbfb7b3ae93a794d8a11
	https://git.kernel.org/stable/c/2926031acba100d0c18fcfaa7a2ed29609318848
	https://git.kernel.org/stable/c/c27e360545373b7aee9862a5beef3b9fb3df0c25