netdev - Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code

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, 17 Dec 2015 15:28:21 +0000
From:	Rainer Weikusat <rweikusat@...ileactivedefense.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>
Subject: Re: [PATCH] af_unix: Revert 'lock_interruptible' in stream receive code

Hannes Frederic Sowa <hannes@...essinduktion.org> writes:
> On 16.12.2015 21:09, Rainer Weikusat wrote:
>> With b3ca9b02b00704053a38bfe4c31dbbb9c13595d0, the AF_UNIX SOCK_STREAM
>> receive code was changed from using mutex_lock(&u->readlock) to
>> mutex_lock_interruptible(&u->readlock) to prevent signals from being
>> delayed for an indefinite time if a thread sleeping on the mutex
>> happened to be selected for handling the signal. But this was never a
>> problem with the stream receive code (as opposed to its datagram
>> counterpart) as that never went to sleep waiting for new messages with the
>> mutex held and thus, wouldn't cause secondary readers to block on the
>> mutex waiting for the sleeping primary reader. As the interruptible
>> locking makes the code more complicated in exchange for no benefit,
>> change it back to using mutex_lock.
>> 
>> Signed-off-by: Rainer Weikusat <rweikusat@...ileactivedefense.com>
>> ---
>> 
>> Considering that the datagram receive routine also doesn't go the sleep
>> with the mutex held anymore, the 37ab4fa7844a044dc21fde45e2a0fc2f3c3b6490
>> change to unix_autobind is now similarly purposeless.
>
> I wouldn't do this conversion, yet. There is still a deadlock lingering
> around which should be solved earlier:
>
> http://lists.openwall.net/netdev/2015/11/10/4
>
> Unfortunately I haven't found a good way how to solve it, yet.

Judging from the link, that's not related to the stream receive code.
--
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