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  • Eric Dumazet's avatar
    tun: properly test for IFF_UP · 4477138f
    Eric Dumazet authored
    Same reasons than the ones explained in commit 4179cb5a
    ("vxlan: test dev->flags & IFF_UP before calling netif_rx()")
    netif_rx_ni() or napi_gro_frags() must be called under a strict contract.
    At device dismantle phase, core networking clears IFF_UP
    and flush_all_backlogs() is called after rcu grace period
    to make sure no incoming packet might be in a cpu backlog
    and still referencing the device.
    A similar protocol is used for gro layer.
    Most drivers call netif_rx() from their interrupt handler,
    and since the interrupts are disabled at device dismantle,
    netif_rx() does not have to check dev->flags & IFF_UP
    Virtual drivers do not have this guarantee, and must
    therefore make the check themselves.
    Fixes: 1bd4978a
     ("tun: honor IFF_UP in tun_get_user()")
    Signed-off-by: default avatarEric Dumazet <>
    Reported-by: default avatarsyzbot <>
    Signed-off-by: default avatarDavid S. Miller <>