linux-kernel - [PATCH] net: Fix error handling in netdev_register

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Message-Id: <20251107080117.15099-1-make24@iscas.ac.cn>
Date: Fri,  7 Nov 2025 16:01:17 +0800
From: Ma Ke <make24@...as.ac.cn>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org,
	sdf@...ichev.me,
	atenart@...nel.org,
	kuniyu@...gle.com,
	yajun.deng@...ux.dev,
	gregkh@...e.de,
	ebiederm@...ssion.com
Cc: netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	Ma Ke <make24@...as.ac.cn>,
	stable@...r.kernel.org
Subject: [PATCH] net: Fix error handling in netdev_register_kobject

After calling device_initialize(), the reference count of the device
is set to 1. If device_add() fails or register_queue_kobjects() fails,
the function returns without calling put_device() to release the
initial reference, causing a memory leak of the device structure.
Similarly, in netdev_unregister_kobject(), after calling device_del(),
there is no call to put_device() to release the initial reference,
leading to a memory leak. Add put_device() in the error paths of
netdev_register_kobject() and after device_del() in
netdev_unregister_kobject() to properly release the device references.

Found by code review.

Cc: stable@...r.kernel.org
Fixes: a1b3f594dc5f ("net: Expose all network devices in a namespaces in sysfs")
Signed-off-by: Ma Ke <make24@...as.ac.cn>
---
 net/core/net-sysfs.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index ca878525ad7c..d3895f26a0c8 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -2327,6 +2327,7 @@ void netdev_unregister_kobject(struct net_device *ndev)
 	pm_runtime_set_memalloc_noio(dev, false);
 
 	device_del(dev);
+	put_device(dev);
 }
 
 /* Create sysfs entries for network device. */
@@ -2357,7 +2358,7 @@ int netdev_register_kobject(struct net_device *ndev)
 
 	error = device_add(dev);
 	if (error)
-		return error;
+		goto out_put_device;
 
 	error = register_queue_kobjects(ndev);
 	if (error) {
@@ -2367,6 +2368,10 @@ int netdev_register_kobject(struct net_device *ndev)
 
 	pm_runtime_set_memalloc_noio(dev, true);
 
+	return 0;
+
+out_put_device:
+	put_device(dev);
 	return error;
 }
 
-- 
2.17.1