From: David Miller <davem@davemloft.net>
To: edumazet@google.com
Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com,
syzkaller@googlegroups.com
Subject: Re: [PATCH net] tun: properly test for IFF_UP
Date: Fri, 15 Mar 2019 15:43:28 -0700 (PDT) [thread overview]
Message-ID: <20190315.154328.1054764537190173229.davem@davemloft.net> (raw)
In-Reply-To: <20190315031947.63245-1-edumazet@google.com>
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 14 Mar 2019 20:19:47 -0700
> Same reasons than the ones explained in commit 4179cb5a4c92
> ("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: 1bd4978a88ac ("tun: honor IFF_UP in tun_get_user()")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
Applied and queued up for -stable, thanks Eric.
next prev parent reply other threads:[~2019-03-15 22:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-15 3:19 [PATCH net] tun: properly test for IFF_UP Eric Dumazet
2019-03-15 22:43 ` David Miller [this message]
2019-03-16 20:02 ` Eric Dumazet
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