From: David Miller <davem@davemloft.net>
To: mkubecek@suse.cz
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
posk@google.com, eric.dumazet@gmail.com, gfigueira@suse.com
Subject: Re: [PATCH net] net: ipv4: do not handle duplicate fragments as overlapping
Date: Wed, 12 Dec 2018 21:42:23 -0800 (PST) [thread overview]
Message-ID: <20181212.214223.211216727717464391.davem@davemloft.net> (raw)
In-Reply-To: <20181213022800.9D298E1116@unicorn.suse.cz>
From: Michal Kubecek <mkubecek@suse.cz>
Date: Thu, 13 Dec 2018 03:28:00 +0100 (CET)
> Since commit 7969e5c40dfd ("ip: discard IPv4 datagrams with overlapping
> segments.") IPv4 reassembly code drops the whole queue whenever an
> overlapping fragment is received. However, the test is written in a way
> which detects duplicate fragments as overlapping so that in environments
> with many duplicate packets, fragmented packets may be undeliverable.
>
> Add an extra test and for (potentially) duplicate fragment, only drop the
> new fragment rather than the whole queue. Only starting offset and length
> are checked, not the contents of the fragments as that would be too
> expensive. Check for duplicity with last (tail) fragment first as in real
> life scenarios this should be the most frequent case and we would have to
> iterate through the whole "run" otherwise.
>
> Fixes: 7969e5c40dfd ("ip: discard IPv4 datagrams with overlapping segments.")
> Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
I'll give Eric a chance to review this, thanks Michal.
next prev parent reply other threads:[~2018-12-13 5:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 2:28 [PATCH net] net: ipv4: do not handle duplicate fragments as overlapping Michal Kubecek
2018-12-13 5:42 ` David Miller [this message]
2018-12-13 6:20 ` Eric Dumazet
2018-12-13 11:27 ` Michal Kubecek
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