linux-kernel - Re: [PATCH] drivers/media/video/ivtv/ivtvfb.c: prevent reading uninitialized stack memory

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Date:	Wed, 15 Sep 2010 20:59:19 -0400
From:	Andy Walls <awalls@...metrocast.net>
To:	Dan Rosenberg <drosenberg@...curity.com>
Cc:	ivtv-devel@...vdriver.org, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, security@...nel.org,
	stable@...nel.org
Subject: Re: [PATCH] drivers/media/video/ivtv/ivtvfb.c: prevent reading
 uninitialized stack memory

Acked-by: Andy Walls <awalls@...metrocast.net>

By tomorrow evening I'll put this in my repo and ask for Mauro to pull it.

Regards,
Andy

Dan Rosenberg <drosenberg@...curity.com> wrote:

>The FBIOGET_VBLANK device ioctl allows unprivileged users to read 16
>bytes of uninitialized stack memory, because the "reserved" member of
>the fb_vblank struct declared on the stack is not altered or zeroed
>before being copied back to the user.  This patch takes care of it.
>
>Signed-off-by: Dan Rosenberg <dan.j.rosenberg@...il.com>
>
>--- linux-2.6.35.4.orig/drivers/media/video/ivtv/ivtvfb.c	2010-08-26 19:47:12.000000000 -0400
>+++ linux-2.6.35.4/drivers/media/video/ivtv/ivtvfb.c	2010-09-15 14:16:46.797375399 -0400
>@@ -458,6 +458,8 @@ static int ivtvfb_ioctl(struct fb_info *
> 			struct fb_vblank vblank;
> 			u32 trace;
> 
>+			memset(&vblank, 0, sizeof(struct fb_vblank));
>+
> 			vblank.flags = FB_VBLANK_HAVE_COUNT |FB_VBLANK_HAVE_VCOUNT |
> 					FB_VBLANK_HAVE_VSYNC;
> 			trace = read_reg(IVTV_REG_DEC_LINE_FIELD) >> 16;
>
>
>
>