linux-kernel - Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and mm->mmap

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: <20090411080415.7fe924a2.krzysztof.h1@poczta.fm>
Date:	Sat, 11 Apr 2009 08:04:15 +0200
From:	Krzysztof Helt <krzysztof.h1@...zta.fm>
To:	Andrea Righi <righi.andrea@...il.com>
Cc:	Eric Miao <eric.y.miao@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Andrey Borzenkov <arvidjaar@...il.com>,
	"Antonino A. Daplas" <adaplas@...il.com>,
	linux-fbdev-devel@...ts.sourceforge.net,
	linux-pm@...ts.linux-foundation.org, Dave Jones <davej@...hat.com>,
	Harvey Harrison <harvey.harrison@...il.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Stefan Richter <stefanr@...6.in-berlin.de>
Subject: Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and
 mm->mmap_sem ...} causes Xfbdev not working

On Sat, 11 Apr 2009 00:05:22 +0200
Andrea Righi <righi.andrea@...il.com> wrote:

> 
> mmmh... I may have missed something, but the common fb_mmap() should
> acquire mm->mmap_sem and then info->lock, while fb_ioctl() can do that
> in reverse order (info->lock first and then mm->mmap_sem) causing the
> circular locking dependency. Are you sure that pushing info->lock down
> each driver's fb_mmap will fix the problem?

Right. The fb_mmap is called with the mmap_sem already held.
I will try other possibilities like breaking info->lock() into two
mutexex.

Something should be done to solve this problem.

Best regards,
Krzysztof

----------------------------------------------------------------------
Oblej swoich znajomych... wirtualnie! ;)
http://link.interia.pl/f2119

--
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/