linux-kernel - [PATCH 5.8 072/232] driver core: Avoid binding drivers to dead devices

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Message-Id: <20200820091616.290353265@linuxfoundation.org>
Date:   Thu, 20 Aug 2020 11:18:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Lukas Wunner <lukas@...ner.de>,
        Alexander Duyck <alexander.h.duyck@...ux.intel.com>
Subject: [PATCH 5.8 072/232] driver core: Avoid binding drivers to dead devices

From: Lukas Wunner <lukas@...ner.de>

commit 654888327e9f655a9d55ad477a9583e90e8c9b5c upstream.

Commit 3451a495ef24 ("driver core: Establish order of operations for
device_add and device_del via bitflag") sought to prevent asynchronous
driver binding to a device which is being removed.  It added a
per-device "dead" flag which is checked in the following code paths:

* asynchronous binding in __driver_attach_async_helper()
*  synchronous binding in device_driver_attach()
* asynchronous binding in __device_attach_async_helper()

It did *not* check the flag upon:

*  synchronous binding in __device_attach()

However __device_attach() may also be called asynchronously from:

deferred_probe_work_func()
  bus_probe_device()
    device_initial_probe()
      __device_attach()

So if the commit's intention was to check the "dead" flag in all
asynchronous code paths, then a check is also necessary in
__device_attach().  Add the missing check.

Fixes: 3451a495ef24 ("driver core: Establish order of operations for device_add and device_del via bitflag")
Signed-off-by: Lukas Wunner <lukas@...ner.de>
Cc: stable@...r.kernel.org # v5.1+
Cc: Alexander Duyck <alexander.h.duyck@...ux.intel.com>
Link: https://lore.kernel.org/r/de88a23a6fe0ef70f7cfd13c8aea9ab51b4edab6.1594214103.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/base/dd.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -844,7 +844,9 @@ static int __device_attach(struct device
 	int ret = 0;
 
 	device_lock(dev);
-	if (dev->driver) {
+	if (dev->p->dead) {
+		goto out_unlock;
+	} else if (dev->driver) {
 		if (device_is_bound(dev)) {
 			ret = 1;
 			goto out_unlock;