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Message-Id: <361bbf2a4b091e120006279ec3b382d73c4a0c17.1715247018.git.duoming@zju.edu.cn>
Date: Thu, 9 May 2024 17:36:47 +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,
jreuter@...na.de,
dan.carpenter@...aro.org,
rkannoth@...vell.com,
davem@...emloft.net,
lars@...bit.com,
Duoming Zhou <duoming@....edu.cn>
Subject: [PATCH net v7 2/3] ax25: Fix reference count leak issues of ax25_dev
The ax25_addr_ax25dev() and ax25_dev_device_down() exist a reference
count leak issue of the object "ax25_dev".
Memory leak issue in ax25_addr_ax25dev():
The reference count of the object "ax25_dev" can be increased multiple
times in ax25_addr_ax25dev(). This will cause a memory leak.
Memory leak issues in ax25_dev_device_down():
The reference count of ax25_dev is set to 1 in ax25_dev_device_up() and
then increase the reference count when ax25_dev is added to ax25_dev_list.
As a result, the reference count of ax25_dev is 2. But when the device is
shutting down. The ax25_dev_device_down() drops the reference count once
or twice depending on if we goto unlock_put or not, which will cause
memory leak.
As for the issue of ax25_addr_ax25dev(), it is impossible for one pointer
to be on a list twice. So add a break in ax25_addr_ax25dev(). As for the
issue of ax25_dev_device_down(), increase the reference count of ax25_dev
once in ax25_dev_device_up() and decrease the reference count of ax25_dev
after it is removed from the ax25_dev_list.
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>
---
net/ax25/ax25_dev.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index f16ee5c09d0..52ccc37d568 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -39,6 +39,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
ax25_dev_hold(ax25_dev);
+ break;
}
spin_unlock_bh(&ax25_dev_lock);
@@ -88,7 +89,6 @@ void ax25_dev_device_up(struct net_device *dev)
list_add(&ax25_dev->list, &ax25_dev_list);
dev->ax25_ptr = ax25_dev;
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_hold(ax25_dev);
ax25_register_dev_sysctl(ax25_dev);
}
@@ -129,7 +129,6 @@ void ax25_dev_device_down(struct net_device *dev)
unlock_put:
dev->ax25_ptr = NULL;
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_put(ax25_dev);
netdev_put(dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
}
--
2.17.1
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