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From: Arnd Bergmann <arnd@arndb.de>
To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Joe Perches <joe@perches.com>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Andrea Righi <righi.andrea@gmail.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Sam Ravnborg <sam@ravnborg.org>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Peter Rosin <peda@axentia.se>, Gerd Hoffmann <kraxel@redhat.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	kernel-janitors@vger.kernel.org, security@kernel.org,
	Kees Cook <keescook@chromium.org>,
	Julia Lawall <Julia.Lawall@lip6.fr>
Subject: Re: [PATCH] fbdev: potential information leak in do_fb_ioctl()
Date: Wed, 15 Jan 2020 14:16:57 +0100	[thread overview]
Message-ID: <CAK8P3a3SJZ+j0jzYGtETaLGUXwwn0WqjN+wojUrYngOui9+h7A@mail.gmail.com> (raw)
In-Reply-To: <6ed59903-afe7-d5b2-73eb-ca626616dd6f@samsung.com>

On Wed, Jan 15, 2020 at 2:09 PM Bartlomiej Zolnierkiewicz
<b.zolnierkie@samsung.com> wrote:

> > $ git grep -wl register_framebuffer | xargs grep -L framebuffer_alloc
> > Documentation/fb/framebuffer.rst
> > drivers/media/pci/ivtv/ivtvfb.c
> > drivers/media/platform/vivid/vivid-osd.c
> > drivers/video/fbdev/68328fb.c
> > drivers/video/fbdev/acornfb.c
> > drivers/video/fbdev/amba-clcd.c
> > drivers/video/fbdev/atafb.c
> > drivers/video/fbdev/au1100fb.c
> > drivers/video/fbdev/controlfb.c
> > drivers/video/fbdev/core/fbmem.c
> > drivers/video/fbdev/cyber2000fb.c
> > drivers/video/fbdev/fsl-diu-fb.c
> > drivers/video/fbdev/g364fb.c
> > drivers/video/fbdev/goldfishfb.c
> > drivers/video/fbdev/hpfb.c
> > drivers/video/fbdev/macfb.c
> > drivers/video/fbdev/matrox/matroxfb_base.c
> > drivers/video/fbdev/matrox/matroxfb_crtc2.c
> > drivers/video/fbdev/maxinefb.c
> > drivers/video/fbdev/ocfb.c
> > drivers/video/fbdev/pxafb.c
> > drivers/video/fbdev/sa1100fb.c
> > drivers/video/fbdev/stifb.c
> > drivers/video/fbdev/valkyriefb.c
> > drivers/video/fbdev/vermilion/vermilion.c
> > drivers/video/fbdev/vt8500lcdfb.c
> > drivers/video/fbdev/wm8505fb.c
> > drivers/video/fbdev/xilinxfb.c
> >
> > It's possible (even likely, the ones I looked at are fine) that they
> > all correctly
> > zero out the fb_info structure first, but it seems hard to guarantee, so
> > Eric's suggestion would possibly still be the safer choice.
>
> I've audited all above instances and they are all fine. They either
> use the fb_info structure embedded in a driver specific structure
> (which is zeroed out) or (in case of some m68k specific drivers) use
> a static fb_info instance.
>
> Since fbdev is closed for new drivers it should be now fine to use
> the simpler approach (just use memcpy()).

Yes, let's do that then. The complex approach seems more likely
to introduce a bug than one of the existing drivers to stop initializing
the structure correctly.

      Arnd

      reply	other threads:[~2020-01-15 13:17 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-29 18:23 [PATCH] fbdev: potential information leak in do_fb_ioctl() Dan Carpenter
2019-10-29 18:35 ` Joe Perches
2019-10-29 19:02 ` Eric W. Biederman
2019-10-30  7:43   ` Andrea Righi
2019-10-30 19:26     ` Eric W. Biederman
2019-10-30 20:12       ` Andrea Righi
2019-10-31 18:16         ` Joe Perches
2019-10-31 22:12           ` Eric W. Biederman
2020-01-03 13:07   ` Bartlomiej Zolnierkiewicz
2020-01-13 11:08     ` [PATCH v2] " Dan Carpenter
2020-01-15 14:31       ` Bartlomiej Zolnierkiewicz
2020-01-13 12:49     ` [PATCH] " Arnd Bergmann
2020-01-15 13:09       ` Bartlomiej Zolnierkiewicz
2020-01-15 13:16         ` Arnd Bergmann [this message]

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