linux-kernel - [PATCH net v3 2/2] ax25: Change kfree() in ax25_dev_free() to ax25_dev

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Message-Id: <53925353450dea9a705d67ad225b589e8508042c.1715002910.git.duoming@zju.edu.cn>
Date: Mon,  6 May 2024 22:08:35 +0800
From: Duoming Zhou <duoming@....edu.cn>
To: netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	linux-hams@...r.kernel.org,
	pabeni@...hat.com,
	kuba@...nel.org,
	edumazet@...gle.com,
	davem@...emloft.net,
	jreuter@...na.de,
	horms@...nel.org,
	Markus.Elfring@....de,
	dan.carpenter@...aro.org,
	lars@...bit.com,
	Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH net v3 2/2] ax25: Change kfree() in ax25_dev_free() to ax25_dev_put()

The object "ax25_dev" is managed by reference counting. Thus it should
not be directly released by a kfree() call in ax25_dev_free(). Replace
it with a ax25_dev_put() call instead.

Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Suggested-by: Dan Carpenter <dan.carpenter@...aro.org>
Signed-off-by: Duoming Zhou <duoming@....edu.cn>
---
Changes in v3:
  - Make commit messages more clearer.

 net/ax25/ax25_dev.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index fbaaba0351e..8ee028e752f 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -188,16 +188,13 @@ struct net_device *ax25_fwd_dev(struct net_device *dev)
  */
 void __exit ax25_dev_free(void)
 {
-	ax25_dev *s, *ax25_dev;
+	ax25_dev *s, *n;
 
 	spin_lock_bh(&ax25_dev_lock);
-	ax25_dev = ax25_dev_list;
-	while (ax25_dev != NULL) {
-		s        = ax25_dev;
-		netdev_put(ax25_dev->dev, &ax25_dev->dev_tracker);
-		ax25_dev = ax25_dev->next;
-		kfree(s);
+	list_for_each_entry_safe(s, n, &ax25_dev_list, list) {
+		netdev_put(s->dev, &s->dev_tracker);
+		list_del(&s->list);
+		ax25_dev_put(s);
 	}
-	ax25_dev_list = NULL;
 	spin_unlock_bh(&ax25_dev_lock);
 }
-- 
2.17.1