linux-kernel - [PATCH v2] intel_th: fix device leak on output open()

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Message-ID: <20251121105555.32725-1-johan@kernel.org>
Date: Fri, 21 Nov 2025 11:55:55 +0100
From: Johan Hovold <johan@...nel.org>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	Johan Hovold <johan@...nel.org>,
	stable@...r.kernel.org
Subject: [PATCH v2] intel_th: fix device leak on output open()

Make sure to drop the reference taken when looking up the th device
during output device open() on errors and on close().

Fixes: 39f4034693b7 ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices")
Cc: stable@...r.kernel.org	# 4.4
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Signed-off-by: Johan Hovold <johan@...nel.org>
---

Hit send too soon...

Changes in v2:
 - drop reference also on the last error path


 drivers/hwtracing/intel_th/core.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 47d9e6c3bac0..bc38814e6802 100644
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -810,13 +810,20 @@ static int intel_th_output_open(struct inode *inode, struct file *file)
 	int err;
 
 	dev = bus_find_device_by_devt(&intel_th_bus, inode->i_rdev);
-	if (!dev || !dev->driver)
+	if (!dev)
 		return -ENODEV;
 
+	if (!dev->driver) {
+		err = -ENODEV;
+		goto err_put_dev;
+	}
+
 	thdrv = to_intel_th_driver(dev->driver);
 	fops = fops_get(thdrv->fops);
-	if (!fops)
-		return -ENODEV;
+	if (!fops) {
+		err = -ENODEV;
+		goto err_put_dev;
+	}
 
 	replace_fops(file, fops);
 
@@ -824,14 +831,29 @@ static int intel_th_output_open(struct inode *inode, struct file *file)
 
 	if (file->f_op->open) {
 		err = file->f_op->open(inode, file);
-		return err;
+		goto err_put_dev;
 	}
 
+	return 0;
+
+err_put_dev:
+	put_device(dev);
+
+	return err;
+}
+
+static int intel_th_output_release(struct inode *inode, struct file *file)
+{
+	struct intel_th_device *thdev = file->private_data;
+
+	put_device(&thdev->dev);
+
 	return 0;
 }
 
 static const struct file_operations intel_th_output_fops = {
 	.open	= intel_th_output_open,
+	.release = intel_th_output_release,
 	.llseek	= noop_llseek,
 };
 
-- 
2.51.2