netdev - Re: [net-next] tun: fix data-race in gro_normal

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Date:   Thu, 14 Nov 2019 10:07:58 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Petar Penkov <ppenkov.kernel@...il.com>
Cc:     netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Petar Penkov <ppenkov@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: Re: [net-next] tun: fix data-race in gro_normal_list()

On Thu, Nov 14, 2019 at 9:52 AM Petar Penkov <ppenkov.kernel@...il.com> wrote:
>
> From: Petar Penkov <ppenkov@...gle.com>
>
> There is a race in the TUN driver between napi_busy_loop and
> napi_gro_frags. This commit resolves the race by adding the NAPI struct
> via netif_tx_napi_add, instead of netif_napi_add, which disables polling
> for the NAPI struct.
>
> KCSAN reported:
> BUG: KCSAN: data-race in gro_normal_list.part.0 / napi_busy_loop
> Fixes: 943170998b20 ("tun: enable NAPI for TUN/TAP driver")
> Signed-off-by: Petar Penkov <ppenkov@...gle.com>
> Reported-by: syzbot <syzkaller@...glegroups.com>
> ---

Reviewed-by: Eric Dumazet <edumazet@...gle.com>