intel_th: Fix error handling in intel_th_output_open

commit 6d5925b667e4ed9e77c8278cc215191d29454a3f upstream.

intel_th_output_open() calls bus_find_device_by_devt() which
internally increments the device reference count via get_device(), but
this reference is not properly released in several error paths. When
device driver is unavailable, file operations cannot be obtained, or
the driver's open method fails, the function returns without calling
put_device(), leading to a permanent device reference count leak. This
prevents the device from being properly released and could cause
resource exhaustion over time.

Found by code review.

Cc: stable <stable@kernel.org>
Fixes: 39f4034693b7 ("intel_th: Add driver infrastructure for Intel(R) Trace Hub devices")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
Link: https://patch.msgid.link/20251112091723.35963-1-make24@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index 9cb8c7d13d46b93b1bf66ecaa0de85cd07d9953e..68af130712bc16ffb453f81758c1dbca3b4a9a02 100644 (file)
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -810,13 +810,17 @@ 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)
-               return -ENODEV;
+       if (!dev || !dev->driver) {
+               err = -ENODEV;
+               goto out_no_device;
+       }
 
        thdrv = to_intel_th_driver(dev->driver);
        fops = fops_get(thdrv->fops);
-       if (!fops)
-               return -ENODEV;
+       if (!fops) {
+               err = -ENODEV;
+               goto out_put_device;
+       }
 
        replace_fops(file, fops);
 
@@ -824,10 +828,16 @@ 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;
+               if (err)
+                       goto out_put_device;
        }
 
        return 0;
+
+out_put_device:
+       put_device(dev);
+out_no_device:
+       return err;
 }
 
 static const struct file_operations intel_th_output_fops = {