From: Duoming Zhou <duoming@zju.edu.cn>
To: linux-hams@vger.kernel.org
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
pabeni@redhat.com, kuba@kernel.org, edumazet@google.com,
davem@davemloft.net, jreuter@yaina.de, dan.carpenter@linaro.org,
lars@oddbit.com, Duoming Zhou <duoming@zju.edu.cn>
Subject: [PATCH net] ax25: Fix refcount leak issues of ax25_dev
Date: Wed, 1 May 2024 14:02:18 +0800 [thread overview]
Message-ID: <20240501060218.32898-1-duoming@zju.edu.cn> (raw)
There are two scenarios that might cause refcount leak
issues of ax25_dev.
Scenario one:
The refcount of ax25_dev potentially increase more
than once in ax25_addr_ax25dev(), which will cause
memory leak.
In order to fix the above issue, only increase the
refcount of ax25_dev once, when the res is not null.
Scenario two:
The original code sets the refcount of ax25_dev to 1
in the initial stage and then increase the refcount
when the ax25_dev is added to the ax25_dev_list. As a
result, the refcount of ax25_dev is 2. But when the
device is shutting down. The ax25_dev_device_down()
drops the refcount once or twice depending on if we
goto unlock_put or not, which will cause memory leak.
In order to mitigate the above issues, only increase
the refcount of ax25_dev when the ax25_dev is added
to the ax25_dev_list and decrease the refcount of
ax25_dev after it is removed from the ax25_dev_list.
What's more, the ax25_dev should not be deallocated
directly by kfree() in ax25_dev_free(), replace it
with ax25_dev_put() instead.
Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs")
Reported by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
net/ax25/ax25_dev.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index 282ec581c07..0e6dd98d3fa 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -37,8 +37,9 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr)
for (ax25_dev = ax25_dev_list; ax25_dev != NULL; ax25_dev = ax25_dev->next)
if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) == 0) {
res = ax25_dev;
- ax25_dev_hold(ax25_dev);
}
+ if (res)
+ ax25_dev_hold(res);
spin_unlock_bh(&ax25_dev_lock);
return res;
@@ -58,7 +59,6 @@ void ax25_dev_device_up(struct net_device *dev)
return;
}
- refcount_set(&ax25_dev->refcount, 1);
dev->ax25_ptr = ax25_dev;
ax25_dev->dev = dev;
netdev_hold(dev, &ax25_dev->dev_tracker, GFP_KERNEL);
@@ -88,7 +88,7 @@ void ax25_dev_device_up(struct net_device *dev)
ax25_dev->next = ax25_dev_list;
ax25_dev_list = ax25_dev;
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_hold(ax25_dev);
+ refcount_set(&ax25_dev->refcount, 1);
ax25_register_dev_sysctl(ax25_dev);
}
@@ -135,7 +135,6 @@ void ax25_dev_device_down(struct net_device *dev)
unlock_put:
spin_unlock_bh(&ax25_dev_lock);
- ax25_dev_put(ax25_dev);
dev->ax25_ptr = NULL;
netdev_put(dev, &ax25_dev->dev_tracker);
ax25_dev_put(ax25_dev);
@@ -208,7 +207,7 @@ void __exit ax25_dev_free(void)
s = ax25_dev;
netdev_put(ax25_dev->dev, &ax25_dev->dev_tracker);
ax25_dev = ax25_dev->next;
- kfree(s);
+ ax25_dev_put(s);
}
ax25_dev_list = NULL;
spin_unlock_bh(&ax25_dev_lock);
--
2.17.1
next reply other threads:[~2024-05-01 6:02 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-01 6:02 Duoming Zhou [this message]
2024-05-01 17:33 ` [PATCH net] ax25: Fix refcount leak issues of ax25_dev Markus Elfring
2024-05-01 17:43 ` Dan Carpenter
2024-05-02 4:35 ` duoming
2024-05-02 7:56 ` Dan Carpenter
2024-05-02 9:30 ` Paolo Abeni
2024-05-02 1:29 ` Lars Kellogg-Stedman
2024-05-03 20:36 ` Dan Carpenter
2024-05-03 23:40 ` Lars Kellogg-Stedman
2024-05-04 12:16 ` Dan Carpenter
2024-05-04 22:16 ` Lars Kellogg-Stedman
2024-05-07 3:18 ` Lars Kellogg-Stedman
2024-05-07 8:08 ` Dan Carpenter
2024-05-07 9:04 ` duoming
2024-05-08 18:27 ` Dan Carpenter
2024-05-09 1:40 ` duoming
2024-05-23 12:30 ` Lars Kellogg-Stedman
2024-05-07 6:38 ` Dan Carpenter
2024-05-15 9:52 ` duoming
2024-05-16 19:20 ` Lars Kellogg-Stedman
[not found] ` <CANnsUMHTZ_P4-C2iGdbakcp_Xk5c-aCO5kYEvaBdOcsaSnK5Pg@mail.gmail.com>
2024-05-20 14:42 ` Kernel 6.9.1 AX.25 Crash Lars Kellogg-Stedman
2024-05-20 14:49 ` Chris Maness
2024-05-21 0:11 ` Chris Maness
2024-05-21 0:48 ` Lars Kellogg-Stedman
2024-05-21 1:38 ` Chris Maness
2024-05-21 2:12 ` Dan Cross
2024-05-21 3:07 ` Chris Maness
2024-05-21 11:47 ` Dave Hibberd
2024-05-21 12:03 ` Chris Maness
2024-05-21 19:20 ` Mike Quin
2024-05-21 23:02 ` Chris Maness
2024-05-21 23:07 ` Mike Quin
2024-05-21 23:17 ` Chris Maness
2024-05-21 15:53 ` David Ranch
2024-05-21 16:28 ` Chris Maness
2024-05-21 18:12 ` Lars Kellogg-Stedman
2024-05-22 15:32 ` Dan Cross
2024-05-22 16:07 ` Chris Maness
2024-05-22 17:06 ` David Ranch
2024-05-22 18:04 ` Dan Cross
2024-05-22 17:54 ` Dan Cross
2024-05-22 18:17 ` Lars Kellogg-Stedman
2024-05-22 18:37 ` Dan Cross
2024-05-22 19:23 ` Lars Kellogg-Stedman
2024-05-22 22:22 ` David Ranch
2024-05-22 22:32 ` Lars Kellogg-Stedman
2024-05-23 0:54 ` Userspace AX.25 stack library [was Re: Kernel 6.9.1 AX.25 Crash] Stuart Longland VK4MSL
2024-05-23 16:32 ` Dan Cross
2024-05-22 16:10 ` Kernel 6.9.1 AX.25 Crash David Ranch
2024-05-22 18:13 ` Lars Kellogg-Stedman
2024-05-23 10:30 ` Dan Carpenter
2024-05-27 17:59 ` Chris Maness
2024-05-04 11:04 ` [PATCH net] ax25: Fix refcount leak issues of ax25_dev Dan Carpenter
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