CVE-2025-40263: Input: cros_ec_keyb - fix an invalid memory access

CVE-2025-40263: Input: cros_ec_keyb - fix an invalid memory access

[Greg Kroah-Hartman]

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

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

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

Input: cros_ec_keyb - fix an invalid memory access

If cros_ec_keyb_register_matrix() isn't called (due to
`buttons_switches_only`) in cros_ec_keyb_probe(), `ckdev->idev` remains
NULL.  An invalid memory access is observed in cros_ec_keyb_process()
when receiving an EC_MKBP_EVENT_KEY_MATRIX event in cros_ec_keyb_work()
in such case.

  Unable to handle kernel read from unreadable memory at virtual address 0000000000000028
  ...
  x3 : 0000000000000000 x2 : 0000000000000000
  x1 : 0000000000000000 x0 : 0000000000000000
  Call trace:
  input_event
  cros_ec_keyb_work
  blocking_notifier_call_chain
  ec_irq_thread

It's still unknown about why the kernel receives such malformed event,
in any cases, the kernel shouldn't access `ckdev->idev` and friends if
the driver doesn't intend to initialize them.

The Linux kernel CVE team has assigned CVE-2025-40263 to this issue.


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

	Fixed in 5.4.302 with commit 7bfd959187f2c7584bb43280bbc7b2846e7a5085
	Fixed in 6.6.118 with commit 9cf59f4724a9ee06ebb06c76b8678ac322e850b7
	Fixed in 6.12.60 with commit 6d81068685154535af06163eb585d6d9663ec7ec
	Fixed in 6.17.10 with commit 2d251c15c27e2dd16d6318425d2f7260cbd47d39
	Fixed in 6.18 with commit e08969c4d65ac31297fcb4d31d4808c789152f68

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-2025-40263
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/input/keyboard/cros_ec_keyb.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/7bfd959187f2c7584bb43280bbc7b2846e7a5085
	https://git.kernel.org/stable/c/9cf59f4724a9ee06ebb06c76b8678ac322e850b7
	https://git.kernel.org/stable/c/6d81068685154535af06163eb585d6d9663ec7ec
	https://git.kernel.org/stable/c/2d251c15c27e2dd16d6318425d2f7260cbd47d39
	https://git.kernel.org/stable/c/e08969c4d65ac31297fcb4d31d4808c789152f68