netdev - Re: [PATCH v2 2/2] net: return early for possible invalid uaddr

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Date:   Wed, 11 Aug 2021 18:11:52 +0200
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Wen Yang <wenyang@...ux.alibaba.com>, davem@...emloft.net,
        David Ahern <dsahern@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] net: return early for possible invalid uaddr



On 8/11/21 5:24 PM, Wen Yang wrote:
> The inet_dgram_connect() first calls inet_autobind() to select an
> ephemeral port, then checks uaddr in udp_pre_connect() or
> __ip4_datagram_connect(), but the port is not released until the socket
> is closed. This could cause performance issues or even exhaust ephemeral
> ports if a malicious user makes a large number of UDP connections with
> invalid uaddr and/or addr_len.
> 
>  

This is a big patch.

Can the malicious user still use a large number of UDP sockets,
with valid uaddr/add_len and consequently exhaust ephemeral ports ?

If yes, it does not seem your patch is helping.

If no, have you tried instead to undo the autobind, if the connect fails ?