From: Eric Dumazet <eric.dumazet@gmail.com>
To: Markus Elfring <Markus.Elfring@web.de>,
netdev@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
Daniel Borkmann <daniel@iogearbox.net>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Hideaki Yoshifuji <yoshfuji@linux-ipv6.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
kernel-janitors@vger.kernel.org, Aditya Pakki <pakki001@umn.edu>,
Kangjie Lu <kjlu@umn.edu>, Navid Emamdoost <emamd001@umn.edu>,
Stephen McCamant <smccaman@umn.edu>
Subject: Re: tcp: Checking a kmemdup() call in tcp_time_wait()
Date: Sun, 13 Oct 2019 12:45:53 -0700 [thread overview]
Message-ID: <124b41aa-7ba5-f00c-ab73-cb8e6a2ae75f@gmail.com> (raw)
In-Reply-To: <a219235e-bad5-8a9d-0f3e-c05d5cb11df1@web.de>
On 10/12/19 7:51 AM, Markus Elfring wrote:
> Hello,
>
> I tried another script for the semantic patch language out.
> This source code analysis approach points out that the implementation
> of the function “tcp_time_wait” contains also a call of the function “kmemdup”.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/tcp_minisocks.c?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n306
> https://elixir.bootlin.com/linux/v5.4-rc2/source/net/ipv4/tcp_minisocks.c#L306
>
> * Do you find the usage of the macro call “BUG_ON” still appropriate at this place?
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/checkpatch.pl?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n4080
>
> * Is there a need to adjust the error handling here?
Presumably the BUG would trigger if a really disturbing bug happened.
There is no chance a timewait socket could be created with a MD5 key,
if the established socket that is the 'parent' of the timewait
has not a MD5 context itself.
The parent socket only could have MD5 context if tcp_md5sig_pool_populated
could have been set to true.
Once tcp_md5sig_pool_populated is true it can never go back to false.
So the bug here would be that a socket had a successful MD5 context,
and following tcp_alloc_md5sig_pool() would return false.
We can discuss of all BUG() in general, some people simply disable
all of them (cf CONFIG_BUG), but this particular one does not seem
specially bad to me, compared to others.
next prev parent reply other threads:[~2019-10-13 19:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-12 14:51 Markus Elfring
2019-10-13 19:45 ` Eric Dumazet [this message]
2019-10-14 6:51 ` Markus Elfring
2019-10-14 12:33 ` Eric Dumazet
2019-10-14 12:50 ` Markus Elfring
2019-10-14 13:15 ` Eric Dumazet
2019-10-14 17:19 ` Markus Elfring
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