netdev - Re: [PATCH net-next] net: remove unsafe skb

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Message-Id: <20181125.102936.907000798531091562.davem@davemloft.net>
Date:   Sun, 25 Nov 2018 10:29:36 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     edumazet@...gle.com
Cc:     netdev@...r.kernel.org, eric.dumazet@...il.com,
        faisal.latif@...el.com, dledford@...hat.com, jgg@...pe.ca,
        linux-rdma@...r.kernel.org
Subject: Re: [PATCH net-next] net: remove unsafe skb_insert()

From: Eric Dumazet <edumazet@...gle.com>
Date: Sun, 25 Nov 2018 08:26:23 -0800

> I do not see how one can effectively use skb_insert() without holding
> some kind of lock. Otherwise other cpus could have changed the list
> right before we have a chance of acquiring list->lock.
> 
> Only existing user is in drivers/infiniband/hw/nes/nes_mgt.c and this
> one probably meant to use __skb_insert() since it appears nesqp->pau_list
> is protected by nesqp->pau_lock. This looks like nesqp->pau_lock
> could be removed, since nesqp->pau_list.lock could be used instead.
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Good find.

Indeed, any of the queue SKB manipulation functions that take two SKBs
as an argument are suspect in this manner.

Applied, thanks Eric.