linux-kernel - [PATCH 5.4 104/129] media: rc: do not access device via sysfs after rc_unregister

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Message-Id: <20200908152235.032347423@linuxfoundation.org>
Date:   Tue,  8 Sep 2020 17:25:45 +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, Sean Young <sean@...s.org>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Subject: [PATCH 5.4 104/129] media: rc: do not access device via sysfs after rc_unregister_device()

From: Sean Young <sean@...s.org>

commit a2e2d73fa28136598e84db9d021091f1b98cbb1a upstream.

Device drivers do not expect to have change_protocol or wakeup
re-programming to be accesed after rc_unregister_device(). This can
cause the device driver to access deallocated resources.

Cc: <stable@...r.kernel.org> # 4.16+
Signed-off-by: Sean Young <sean@...s.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/rc/rc-main.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -1256,6 +1256,10 @@ static ssize_t store_protocols(struct de
 	}
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	old_protocols = *current_protocols;
 	new_protocols = old_protocols;
@@ -1394,6 +1398,10 @@ static ssize_t store_filter(struct devic
 		return -EINVAL;
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	new_filter = *filter;
 	if (fattr->mask)
@@ -1508,6 +1516,10 @@ static ssize_t store_wakeup_protocols(st
 	int i;
 
 	mutex_lock(&dev->lock);
+	if (!dev->registered) {
+		mutex_unlock(&dev->lock);
+		return -ENODEV;
+	}
 
 	allowed = dev->allowed_wakeup_protocols;