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sit: proper dev_{hold|put} in ndo_[un]init methods

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commit 6289a98f0817a4a457750d6345e754838eae9439 upstream.

After adopting CONFIG_PCPU_DEV_REFCNT=n option, syzbot was able to trigger
a warning [1]

Issue here is that:

- all dev_put() should be paired with a corresponding prior dev_hold().

- A driver doing a dev_put() in its ndo_uninit() MUST also
  do a dev_hold() in its ndo_init(), only when ndo_init()
  is returning 0.

Otherwise, register_netdevice() would call ndo_uninit()
in its error path and release a refcount too soon.

Fixes: 919067cc845f ("net: add CONFIG_PCPU_DEV_REFCNT")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet 2021-03-29 12:25:22 -07:00 committed by Greg Kroah-Hartman
parent cca2a2b340
commit f5ddecb6a1
1 changed files with 1 additions and 3 deletions
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4
net/ipv6/sit.c
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@ -211,8 +211,6 @@ static int ipip6_tunnel_create(struct net_device *dev)
ipip6_tunnel_clone_6rd(dev, sitn);
dev_hold(dev);
ipip6_tunnel_link(sitn, t);
return 0;
@ -1408,7 +1406,7 @@ static int ipip6_tunnel_init(struct net_device *dev)
dev->tstats = NULL;
return err;
}
dev_hold(dev);
return 0;
}