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net: bridge: fix net device refcount tracking issue in error path 

I left one dev_put() in br_add_if() error path and sure enough
syzbot found its way.

As the tracker is allocated in new_nbp(), we must make sure
to properly free it.

We have to call dev_put_track(dev, &p->dev_tracker) before
@p object is freed, of course. This is not an issue because
br_add_if() owns a reference on @dev.

Fixes: b2dcdc7f73 ("net: bridge: add net device refcount tracker")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2022-01-12 04:53:00 -08:00 committed by David S. Miller
parent 0bbed88af5
commit fcfb894d59
1 changed files with 2 additions and 1 deletions
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3
net/bridge/br_if.c
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@ -615,6 +615,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
err = dev_set_allmulti(dev, 1);
if (err) {
br_multicast_del_port(p);
dev_put_track(dev, &p->dev_tracker);
kfree(p); /* kobject not yet init'd, manually free */
goto err1;
}
@ -724,10 +725,10 @@ err3:
sysfs_remove_link(br->ifobj, p->dev->name);
err2:
br_multicast_del_port(p);
dev_put_track(dev, &p->dev_tracker);
kobject_put(&p->kobj);
dev_set_allmulti(dev, -1);
err1:
dev_put(dev);
return err;
}