linux-kernel - [PATCH] cpufreq: nforce2: fix reference count leak in nforce2

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Message-Id: <20251027150447.58433-1-linmq006@gmail.com>
Date: Mon, 27 Oct 2025 23:04:45 +0800
From: Miaoqian Lin <linmq006@...il.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: linmq006@...il.com,
	stable@...r.kernel.org
Subject: [PATCH] cpufreq: nforce2: fix reference count leak in nforce2

There are two reference count leaks in this driver:

1. In nforce2_fsb_read(): pci_get_subsys() increases the reference count
   of the PCI device, but pci_dev_put() is never called to release it,
   thus leaking the reference.

2. In nforce2_detect_chipset(): pci_get_subsys() gets a reference to the
   nforce2_dev which is stored in a global variable, but the reference
   is never released when the module is unloaded.

Fix both by:
- Adding pci_dev_put(nforce2_sub5) in nforce2_fsb_read() after reading
  the configuration.
- Adding pci_dev_put(nforce2_dev) in nforce2_exit() to release the
  global device reference.

Found via static analysis.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@...r.kernel.org
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
 drivers/cpufreq/cpufreq-nforce2.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/cpufreq/cpufreq-nforce2.c b/drivers/cpufreq/cpufreq-nforce2.c
index fedad1081973..fbbbe501cf2d 100644
--- a/drivers/cpufreq/cpufreq-nforce2.c
+++ b/drivers/cpufreq/cpufreq-nforce2.c
@@ -145,6 +145,8 @@ static unsigned int nforce2_fsb_read(int bootfsb)
 	pci_read_config_dword(nforce2_sub5, NFORCE2_BOOTFSB, &fsb);
 	fsb /= 1000000;
 
+	pci_dev_put(nforce2_sub5);
+
 	/* Check if PLL register is already set */
 	pci_read_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8 *)&temp);
 
@@ -426,6 +428,7 @@ static int __init nforce2_init(void)
 static void __exit nforce2_exit(void)
 {
 	cpufreq_unregister_driver(&nforce2_driver);
+	pci_dev_put(nforce2_dev);
 }
 
 module_init(nforce2_init);
-- 
2.39.5 (Apple Git-154)