CVE-2026-64589: i2c: core: fix NULL-deref on adapter registration failure

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

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

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

i2c: core: fix NULL-deref on adapter registration failure

If adapter registration ever fails the release callback would trigger a
NULL-pointer dereference as the completion struct has not been
initialised.

Note that before the offending commit this would instead have resulted
in a minor memory leak of the adapter name.

The Linux kernel CVE team has assigned CVE-2026-64589 to this issue.


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

	Issue introduced in 6.12.11 with commit e19f31169f85c712c9fca35bfd28ceb093a9f574 and fixed in 6.12.96 with commit 2ce0a74bfa3acdfcdb00cf02f181f2754b451f42
	Issue introduced in 6.13 with commit 3f8c4f5e9a57868fa107016c81165686d23325f2 and fixed in 6.18.39 with commit 3351c5e77749a0c8a1e252b95420c143ebcf07ac
	Issue introduced in 6.13 with commit 3f8c4f5e9a57868fa107016c81165686d23325f2 and fixed in 7.1.4 with commit 034e307428119b67f5f18a35e4f4e7d15a2b9774
	Issue introduced in 6.13 with commit 3f8c4f5e9a57868fa107016c81165686d23325f2 and fixed in 7.2-rc1 with commit 2295d2bb101faa663fbc45fadbb3fec45f107441

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-2026-64589
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/i2c/i2c-core-base.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/2ce0a74bfa3acdfcdb00cf02f181f2754b451f42
	https://git.kernel.org/stable/c/3351c5e77749a0c8a1e252b95420c143ebcf07ac
	https://git.kernel.org/stable/c/034e307428119b67f5f18a35e4f4e7d15a2b9774
	https://git.kernel.org/stable/c/2295d2bb101faa663fbc45fadbb3fec45f107441