Re: [PATCH bpf] xdp: fix potential deadlock on socket mutex

[Daniel Borkmann]

On 07/08/2019 01:03 PM, Ilya Maximets wrote:
> There are 2 call chains:
> 
>   a) xsk_bind --> xdp_umem_assign_dev
>   b) unregister_netdevice_queue --> xsk_notifier
> 
> with the following locking order:
> 
>   a) xs->mutex --> rtnl_lock
>   b) rtnl_lock --> xdp.lock --> xs->mutex
> 
> Different order of taking 'xs->mutex' and 'rtnl_lock' could produce a
> deadlock here. Fix that by moving the 'rtnl_lock' before 'xs->lock' in
> the bind call chain (a).
> 
> Reported-by: syzbot+bf64ec93de836d7f4c2c@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 455302d1c9ae ("xdp: fix hang while unregistering device bound to xdp socket")
> Signed-off-by: Ilya Maximets <i.maximets@xxxxxxxxxxx>

Applied, thanks!