From: Herbert Xu <herbert@gondor.apana.org.au>
To: Abhishek Shah <abhishek.shah@columbia.edu>
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
netdev@vger.kernel.org, pabeni@redhat.com,
steffen.klassert@secunet.com, linux-kernel@vger.kernel.org,
Gabriel Ryan <gabe@cs.columbia.edu>,
Fan Du <fan.du@windriver.com>
Subject: Re: Race 1 in net/xfrm/xfrm_algo.c
Date: Fri, 29 Jul 2022 10:30:31 +0800 [thread overview]
Message-ID: <YuNGR/5U5pSo6YM3@gondor.apana.org.au> (raw)
In-Reply-To: <CAEHB249ygptvp9wpynMF7zZ2Kcet0+bwLVuVg5UReZHOU1+8HA@mail.gmail.com>
On Thu, Jul 28, 2022 at 08:00:00PM -0400, Abhishek Shah wrote:
> Dear Herbert,
>
> Thanks for your quick reply and sorry for not being more clear about the
> inconsistencies. We identified security implications when algorithms
> disappear or reappear during the execution of *compose_sadb_supported*.
>
> In more detail,
>
> 1) If after *xfrm_count_pfkey_auth_supported* has finished counting the
> available algos, a secondary thread changes the availability of an algo
> through *xfrm_probe_algs*, it will return an incorrect number of available
> algorithms. If an algo was added during the racing access, the code
> allocates a buffer that is smaller than the number of available algorithms
> at net/key/af_key.c#L1619
> <https://elixir.bootlin.com/linux/v5.18-rc5/source/net/key/af_key.c#L1619>.
> This will result in an out of bounds write when the buffer is later
> populated at net/key/af_key.c#L1657
> <https://elixir.bootlin.com/linux/v5.18-rc5/source/net/key/af_key.c#L1657>.
OK this is a real bug caused by this commit:
commit 283bc9f35bbbcb0e9ab4e6d2427da7f9f710d52d
Author: Fan Du <fan.du@windriver.com>
Date: Thu Nov 7 17:47:50 2013 +0800
xfrm: Namespacify xfrm state/policy locks
It neglected to convert xfrm_probe_algs to namespaces so the
previous assumption of exclusive ownership of xfrm_algo_list
by the current afkey request is no longer true.
Thanks,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2022-07-29 2:31 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAEHB24-9hXY+TgQKxJB4bE9a9dFD9C+Lan+ShBwpvwaHVAGMFg@mail.gmail.com>
2022-07-22 3:16 ` Race 1 in net/xfrm/xfrm_algo.c Herbert Xu
[not found] ` <CAEHB249ygptvp9wpynMF7zZ2Kcet0+bwLVuVg5UReZHOU1+8HA@mail.gmail.com>
2022-07-29 2:30 ` Herbert Xu [this message]
2022-08-04 10:03 ` [PATCH] af_key: Do not call xfrm_probe_algs in parallel Herbert Xu
2022-08-09 5:47 ` Steffen Klassert
2022-08-22 16:19 ` Gabriel Ryan
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