linux-kernel - Re: lockdep splat from ioctl and mmap fops sharing lock

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]

Message-ID: <4902E2FA.10209@s5r6.in-berlin.de>
Date:	Sat, 25 Oct 2008 11:12:26 +0200
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Johannes Weiner <hannes@...urebad.de>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrea Righi <righi.andrea@...il.com>,
	Dave Jones <davej@...hat.com>, Dave Airlie <airlied@...hat.com>
Subject: Re: lockdep splat from ioctl and mmap fops sharing lock

Johannes Weiner wrote:
> Stefan Richter <stefanr@...6.in-berlin.de> writes:
> 
>> Johannes Weiner wrote:
>>> raw1394_ioctl() doing usercopy under fi->state_mutex
>>> raw1394_mmap() taking fi->state_mutex under mmap_sem
...
>> was the usage of mmap_sem changed after 2.6.27 or were my tests
>> insufficient?
> 
> In linux-next/-mm, copy_to/from_user have lockdep annotations telling
> that they might fault and therefor acquire the mmap_sem in #PF.
> 
> But since faults on ioctl parameters are so rare, without these
> annotations you would probably never see a warning.

Thanks for the report and explanation.  I logged this as 
http://bugzilla.kernel.org/show_bug.cgi?id=11823 (dv1394, won't fix) and 
http://bugzilla.kernel.org/show_bug.cgi?id=11824 (raw1394, to be fixed 
in the 2.6.28-rc timeframe since it is a post 2.6.27 regression).
-- 
Stefan Richter
-=====-==--- =-=- ==--=
http://arcgraph.de/sr/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/