netdev - Re: [PATCH] udp: fix integer overflow while computing available space in sk

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Message-Id: <20191224.145443.2006645470880449664.davem@davemloft.net>
Date:   Tue, 24 Dec 2019 14:54:43 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     amessina@...gle.com
Cc:     kuznet@....inr.ac.ru, yoshfuji@...ux-ipv6.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] udp: fix integer overflow while computing available
 space in sk_rcvbuf

From: Antonio Messina <amessina@...gle.com>
Date: Thu, 19 Dec 2019 15:08:03 +0100

> When the size of the receive buffer for a socket is close to 2^31 when
> computing if we have enough space in the buffer to copy a packet from
> the queue to the buffer we might hit an integer overflow.
> 
> When an user set net.core.rmem_default to a value close to 2^31 UDP
> packets are dropped because of this overflow. This can be visible, for
> instance, with failure to resolve hostnames.
> 
> This can be fixed by casting sk_rcvbuf (which is an int) to unsigned
> int, similarly to how it is done in TCP.
> 
> Signed-off-by: Antonio Messina <amessina@...gle.com>

Applied and queued up for -stable, thanks.