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 so far.
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 <[email protected]>
Signed-off-by: Duoming Zhou <[email protected]>
---
Changes in v4:
- Make the fix procedure of ax25_dev as a separate update steps.
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 d4e1e36a6a8..6a572fe1046 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -38,6 +38,7 @@ 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);
@@ -90,7 +91,6 @@ 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);
}
@@ -131,7 +131,6 @@ 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