netdev - Re: [PATCH -next v2] unix stream: Fix use-after-free crashes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 8 Sep 2011 12:05:38 +0200
From:	Sedat Dilek <sedat.dilek@...glemail.com>
To:	Tim Chen <tim.c.chen@...ux.intel.com>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	"Yan, Zheng" <zheng.z.yan@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"sfr@...b.auug.org.au" <sfr@...b.auug.org.au>,
	"jirislaby@...il.com" <jirislaby@...il.com>, alex.shi@...el.com
Subject: Re: [PATCH -next v2] unix stream: Fix use-after-free crashes

On Tue, Sep 6, 2011 at 9:59 PM, Tim Chen <tim.c.chen@...ux.intel.com> wrote:
> On Tue, 2011-09-06 at 21:43 +0200, Eric Dumazet wrote:
>> Le mardi 06 septembre 2011 à 12:33 -0700, Tim Chen a écrit :
>>
>> > Yes, I think locking the sendmsg for the entire duration of
>> > unix_stream_sendmsg makes a lot of sense.  It simplifies the logic a lot
>> > more.  I'll try to cook something up in the next couple of days.
>>
>> Thats not really possible, we cant hold a spinlock and call
>> sock_alloc_send_skb() and/or memcpy_fromiovec(), wich might sleep.
>>
>> You would need to prepare the full skb list, then :
>> - stick the ref on the last skb of the list.
>>
>> Transfert the whole skb list in other->sk_receive_queue in one go,
>> instead of one after another.
>>
>> Unfortunately, this would break streaming (big send(), and another
>> thread doing the receive)
>>
>> Listen, I am wondering why hackbench even triggers SCM code. This is
>> really odd. We should not have a _single_ pid/cred ref/unref at all.
>>
>
> Hackbench triggers the code because it has a bunch of threads sending
> msgs on UNIX socket.
>>
>

# lsof | grep socket | wc -l
198

Aprrox 200 sockets in usage here, can you post your hackbench line, please?
I would compare hackbench results with and without new improvements in SCM code.

- Sedat -

[...]
>
> Tim
>
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html