linux-kernel - [34-longterm 117/209] V4L/DVB: ivtvfb: prevent reading uninitialized stack memory

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Date:	Thu, 14 Apr 2011 13:54:35 -0400
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	stable@...nel.org, linux-kernel@...r.kernel.org
Cc:	stable-review@...nel.org, Dan Rosenberg <drosenberg@...curity.com>,
	Dan Rosenberg <dan.j.rosenberg@...il.com>,
	Andy Walls <awalls@...metrocast.net>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>
Subject: [34-longterm 117/209] V4L/DVB: ivtvfb: prevent reading uninitialized stack memory

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

  =====================================================================
  | This is a commit scheduled for the next v2.6.34 longterm release. |
  | If you see a problem with using this for longterm, please comment.|
  =====================================================================

commit 405707985594169cfd0b1d97d29fcb4b4c6f2ac9 upstream.

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>
Signed-off-by: Andy Walls <awalls@...metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@...driver.com>
---
 drivers/media/video/ivtv/ivtvfb.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/media/video/ivtv/ivtvfb.c b/drivers/media/video/ivtv/ivtvfb.c
index de2ff1c..e320b7e 100644
--- a/drivers/media/video/ivtv/ivtvfb.c
+++ b/drivers/media/video/ivtv/ivtvfb.c
@@ -458,6 +458,8 @@ static int ivtvfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long ar
 			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(0x028c0) >> 16;
-- 
1.7.4.4

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