netdev - Re: [PATCH net] vxlan: Fix GRO cells race condition between receive and link delete

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Message-ID: <4a7fdc38-16ed-0faa-b7ec-94f591002def@gmail.com>
Date:   Fri, 8 Mar 2019 09:03:23 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Stefano Brivio <sbrivio@...hat.com>,
        "'David S . Miller'" <davem@...emloft.net>
Cc:     Jianlin Shi <jishi@...hat.com>,
        Sabrina Dubroca <sd@...asysnail.net>,
        Tom Herbert <tom@...bertland.com>, netdev@...r.kernel.org
Subject: Re: [PATCH net] vxlan: Fix GRO cells race condition between receive
 and link delete



On 03/08/2019 07:40 AM, Stefano Brivio wrote:
> If we receive a packet while deleting a VXLAN device, there's a chance
> vxlan_rcv() is called at the same time as vxlan_dellink(). This is fine,
> except that vxlan_dellink() should never ever touch stuff that's still in
> use, such as the GRO cells list.
> 
> Otherwise, vxlan_rcv() crashes while queueing packets via
> gro_cells_receive().
> 
> Move the gro_cells_destroy() to vxlan_uninit(), which runs after the RCU
> grace period is elapsed and nothing needs the gro_cells anymore.
> 
> This is now done in the same way as commit 8e816df87997 ("geneve: Use GRO
> cells infrastructure.") originally implemented for GENEVE.
> 
> Reported-by: Jianlin Shi <jishi@...hat.com>
> Fixes: 58ce31cca1ff ("vxlan: GRO support at tunnel layer")
> Signed-off-by: Stefano Brivio <sbrivio@...hat.com>
> Reviewed-by: Sabrina Dubroca <sd@...asysnail.net>

Nice catch, thanks.

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