linux-kernel - [char-misc-next 1/2] mei: bus: disallow driver match while dismantling device

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Message-Id: <20230207115520.846232-1-tomas.winkler@intel.com>
Date:   Tue,  7 Feb 2023 13:55:19 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        Vitaly Lubart <vitaly.lubart@...el.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>
Subject: [char-misc-next 1/2] mei: bus: disallow driver match while dismantling device

From: Alexander Usyskin <alexander.usyskin@...el.com>

With immediate reply support to enum request and
FW reset, a device on MEI bus can be temporarily removed.
A driver for a device on MEI bus can try to bind to the device
right between bus attempt to remove driver and device
structures removal.
This leaves device driver with pointers to freed memory
of device structures.

Avoid bus device driver bind while dismantling device by
disallowing device match right before driver release.

Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
---
 drivers/misc/mei/bus.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/mei/bus.c b/drivers/misc/mei/bus.c
index a81b890c7ee6..71d53d7ffdba 100644
--- a/drivers/misc/mei/bus.c
+++ b/drivers/misc/mei/bus.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (c) 2012-2019, Intel Corporation. All rights reserved.
+ * Copyright (c) 2012-2023, Intel Corporation. All rights reserved.
  * Intel Management Engine Interface (Intel MEI) Linux driver
  */
 
@@ -1392,6 +1392,7 @@ static int mei_cl_bus_dev_add(struct mei_cl_device *cldev)
  */
 static void mei_cl_bus_dev_stop(struct mei_cl_device *cldev)
 {
+	cldev->do_match = 0;
 	if (cldev->is_added)
 		device_release_driver(&cldev->dev);
 }
-- 
2.39.1