[PATCH] bus: fsl-mc: fix device reference leak in fsl_mc_device_lookup()

[PATCH] bus: fsl-mc: fix device reference leak in fsl_mc_device_lookup()

[Wentao Liang]

The device_find_child() function calls the get_device() and returns a
device reference that must be properly released when no longer needed.
The fsl_mc_device_lookup() directly returns without releasing the
reference via put_device().

Add the missing put_device() call to prevent reference leaks.

Fixes: f2f2726b62f5 ("staging: fsl-mc: Device driver for FSL-MC DPRC devices")
Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/bus/fsl-mc/dprc-driver.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/fsl-mc/dprc-driver.c b/drivers/bus/fsl-mc/dprc-driver.c
index c63a7e688db6..e92c75cef90c 100644
--- a/drivers/bus/fsl-mc/dprc-driver.c
+++ b/drivers/bus/fsl-mc/dprc-driver.c
@@ -124,11 +124,17 @@ struct fsl_mc_device *fsl_mc_device_lookup(struct fsl_mc_obj_desc *obj_desc,
 					   struct fsl_mc_device *mc_bus_dev)
 {
 	struct device *dev;
+	struct fsl_mc_device *mc_dev;
 
 	dev = device_find_child(&mc_bus_dev->dev, obj_desc,
 				__fsl_mc_device_match);
+	if (!dev)
+		return NULL;
+
+	mc_dev = to_fsl_mc_device(dev);
+	put_device(dev);
 
-	return dev ? to_fsl_mc_device(dev) : NULL;
+	return mc_dev;
 }
 
 /**
-- 
2.42.0.windows.2

Re: [PATCH] bus: fsl-mc: fix device reference leak in fsl_mc_device_lookup()

[Ioana Ciornei]

On Thu, Oct 23, 2025 at 11:05:58PM +0800, Wentao Liang wrote:
> The device_find_child() function calls the get_device() and returns a
> device reference that must be properly released when no longer needed.

The release should be done when no longer needed, not even before
returning the device to the caller.

> The fsl_mc_device_lookup() directly returns without releasing the
> reference via put_device().
> 
> Add the missing put_device() call to prevent reference leaks.
> 

No, the call to put_device should not be done from fsl_mc_device_lookup()
but instead from its callers when indeed the device is no longer in use.
For example, fsl_mc_obj_device_add() does call put_device().

Ioana