linux-kernel - [char-misc-next v4 0/3] mei: fix mei

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Message-ID: <20250717141112.1696482-1-alexander.usyskin@intel.com>
Date: Thu, 17 Jul 2025 17:11:09 +0300
From: Alexander Usyskin <alexander.usyskin@...el.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Reuven Abliyev <reuven.abliyev@...el.com>,
	Alexander Usyskin <alexander.usyskin@...el.com>,
	linux-kernel@...r.kernel.org
Subject: [char-misc-next v4 0/3] mei: fix mei_device lifetime

mei_device data structure is allocated using devm_* functions
and hooked to the parent device.
It works for client systems where parent device is pci one.
When parent device is auxiliary bus device produced by
graphics driver, the parent can be destroyed before child
and on the way it cleans all allocated memory.
This leads to use-after-free if mei character device is
opened when parent device is destroyed.

Connect mei_device structure lifteme to mei class device lifetime
by adding mei_device free to class device remove callback.
Decouple character device lifetime from parwnt structure lifetime.

As dev pointer in mei_device structure is converted to non-pointer
device all dev_* calls should be touched in this patch series.

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/14201

V2: Make cdev patches first to avoid double refcounting
    in the middle of the series.
    Replace manual refcount with special device.

V3: Use existing class device by Greg's insight, thanks!

V4: Merge cdev patches into main patch as cdev patches do not fix
    lifetime by itself and can't be merged standalone.
    This creates confusion in review and possibility of broken
    driver if only cdev patches are merged anywhere.

Alexander Usyskin (3):
  mei: bus: use cldev in prints
  mei: more prints with client prefix
  mei: hook mei_device on class device

 drivers/misc/mei/bus-fixup.c    |  16 ++--
 drivers/misc/mei/bus.c          |  42 +++++-----
 drivers/misc/mei/client.c       |  82 +++++++++----------
 drivers/misc/mei/client.h       |   6 +-
 drivers/misc/mei/dma-ring.c     |   8 +-
 drivers/misc/mei/gsc-me.c       |  16 ++--
 drivers/misc/mei/hbm.c          | 135 +++++++++++++++-----------------
 drivers/misc/mei/hw-me.c        | 100 +++++++++++------------
 drivers/misc/mei/hw-txe.c       |  60 +++++++-------
 drivers/misc/mei/init.c         |  47 ++++++-----
 drivers/misc/mei/interrupt.c    |  47 ++++++-----
 drivers/misc/mei/main.c         | 135 +++++++++++++++++++-------------
 drivers/misc/mei/mei_dev.h      |  12 +--
 drivers/misc/mei/pci-me.c       |  20 ++---
 drivers/misc/mei/pci-txe.c      |   4 +-
 drivers/misc/mei/platform-vsc.c |  26 +++---
 16 files changed, 390 insertions(+), 366 deletions(-)

-- 
2.43.0