linux-kernel - [PATCH] media: pci: intel: Balance device refcount when destroying devices

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Message-Id: <20250714132526.3216569-1-make24@iscas.ac.cn>
Date: Mon, 14 Jul 2025 21:25:26 +0800
From: Ma Ke <make24@...as.ac.cn>
To: mchehab@...nel.org,
	ribalda@...omium.org,
	rafael.j.wysocki@...el.com,
	dongcheng.yan@...el.com,
	gregkh@...uxfoundation.org,
	make24@...as.ac.cn,
	peterz@...radead.org,
	wentong.wu@...el.com,
	sakari.ailus@...ux.intel.com,
	andriy.shevchenko@...ux.intel.com
Cc: linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: [PATCH] media: pci: intel: Balance device refcount when destroying devices

Using ipu_bridge_get_ivsc_csi_dev() to locate the device could cause
an imbalance in the device's reference count.
ipu_bridge_get_ivsc_csi_dev() calls device_find_child_by_name() to
implement the localization, and device_find_child_by_name() calls an
implicit get_device() to increment the device's reference count before
returning the pointer. Throughout the entire implementation process,
no mechanism releases resources properly. This leads to a memory leak
because the reference count of the device is never decremented.

As the comment of device_find_child_by_name() says, 'NOTE: you will
need to drop the reference with put_device() after use'.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: c66821f381ae ("media: pci: intel: Add IVSC support for IPU bridge driver")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 drivers/media/pci/intel/ipu-bridge.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/pci/intel/ipu-bridge.c b/drivers/media/pci/intel/ipu-bridge.c
index 83e682e1a4b7..f8b4672accab 100644
--- a/drivers/media/pci/intel/ipu-bridge.c
+++ b/drivers/media/pci/intel/ipu-bridge.c
@@ -192,6 +192,7 @@ static int ipu_bridge_check_ivsc_dev(struct ipu_sensor *sensor,

 		sensor->csi_dev = csi_dev;
 		sensor->ivsc_adev = adev;
+		put_device(csi_dev);
 	}

 	return 0;
-- 
2.25.1