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From: Vladimir Davydov <vdavydov.dev@gmail.com>
To: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Cc: tarantool-patches@freelists.org
Subject: Re: [PATCH 1/1] iproto: protect from false-correct size in msg header
Date: Tue, 19 Jun 2018 14:57:40 +0300	[thread overview]
Message-ID: <20180619115740.ezt2aue5gccoppdv@esperanza> (raw)
In-Reply-To: <c3d064b141e17e8c5fbc4d852e61615c8b4edd4a.1529351502.git.v.shpilevoy@tarantool.org>

Looks OK to me.

On Mon, Jun 18, 2018 at 10:53:01PM +0300, Vladislav Shpilevoy wrote:
> Consider this packet:
> 
>     msgpack = require('msgpack')
>     data = msgpack.encode(18400000000000000000)..'aaaaaaa'
> 
> Tarantool interprets 18400000000000000000 as size of a coming
> iproto request, and tries with no any checks to allocate buffer
> of such size. It calculates needed capacity like this:
> 
>     capacity = start_value;
>     while (capacity < size)
>         capacity *= 2;
> 
> Here it is possible that on i-th iteration 'capacity' < 'size',
> but 'capacity * 2' overflows 64 bits and becomes < 'size' again,
> so this loop never ends and occupies 100% CPU.
> 
> Strictly speaking overflow has undefined behavior. On the
> original system it led to nullifying 'capacity'.
> 
> Such size is improbable as a real packet gabarits, but can appear
> as a result of parsing of some invalid packet, first bytes of
> which accidentally appears to be valid MessagePack uint. This is
> how the bug emerged on the real system.
> 
> Lets restrict the maximal packet size to 2GB.
> 
> Closes #3464
> ---
> Branch: https://github.com/tarantool/tarantool/tree/gerold103/gh-3464-iproto-100-cpu
> Issue: https://github.com/tarantool/tarantool/issues/3464
> 
>  src/box/iproto.cc         | 15 +++++++++++++--
>  test/box/net.box.result   | 22 ++++++++++++++++++++++
>  test/box/net.box.test.lua | 10 ++++++++++
>  3 files changed, 45 insertions(+), 2 deletions(-)

  reply	other threads:[~2018-06-19 11:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-18 19:53 Vladislav Shpilevoy
2018-06-19 11:57 ` Vladimir Davydov [this message]
2018-06-25 13:55 ` [tarantool-patches] " Konstantin Osipov
2018-06-25 14:00   ` [tarantool-patches] [PATCH v2 " Vladislav Shpilevoy
2018-06-25 17:17     ` [tarantool-patches] " Konstantin Osipov

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