[PATCH net] net: lapbether: fix issue of dev reference count leakage in lapbeth_device_event()

[PATCH net] net: lapbether: fix issue of dev reference count leakage in lapbeth_device_event()

[Zhengchao Shao]

When following tests are performed, it will cause dev reference counting
leakage.
a)ip link add bond2 type bond mode balance-rr
b)ip link set bond2 up
c)ifenslave -f bond2 rose1
d)ip link del bond2

When new bond device is created, the default type of the bond device is
ether. And the bond device is up, lapbeth_device_event() receives the
message and creates a new lapbeth device. In this case, the reference
count value of dev is hold once. But after "ifenslave -f bond2 rose1"
command is executed, the type of the bond device is changed to rose. When
the bond device is unregistered, lapbeth_device_event() will not put the
dev reference count.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
 drivers/net/wan/lapbether.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c
index 960f1393595c..cb360dca3250 100644
--- a/drivers/net/wan/lapbether.c
+++ b/drivers/net/wan/lapbether.c
@@ -446,7 +446,7 @@ static int lapbeth_device_event(struct notifier_block *this,
 	if (dev_net(dev) != &init_net)
 		return NOTIFY_DONE;
 
-	if (!dev_is_ethdev(dev))
+	if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev))
 		return NOTIFY_DONE;
 
 	switch (event) {
-- 
2.17.1

Re: [PATCH net] net: lapbether: fix issue of dev reference count leakage in lapbeth_device_event()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Thu, 3 Nov 2022 17:05:37 +0800 you wrote:
> When following tests are performed, it will cause dev reference counting
> leakage.
> a)ip link add bond2 type bond mode balance-rr
> b)ip link set bond2 up
> c)ifenslave -f bond2 rose1
> d)ip link del bond2
> 
> [...]

Here is the summary with links:
  - [net] net: lapbether: fix issue of dev reference count leakage in lapbeth_device_event()
    https://git.kernel.org/netdev/net/c/531705a76549

You are awesome, thank you!
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