linux-kernel - [PATCH 3.2 62/74] video: fbdev: aty: do not leak uninitialized padding in clk to userspace

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Message-ID: <lsq.1507552234.400802101@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:30:34 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Bartlomiej Zolnierkiewicz" <b.zolnierkie@...sung.com>,
        "sohu0106" <sohu0106@....com>, "Vladis Dronov" <vdronov@...hat.com>
Subject: [PATCH 3.2 62/74] video: fbdev: aty: do not leak uninitialized
 padding in clk to userspace

3.2.94-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Vladis Dronov <vdronov@...hat.com>

commit 8e75f7a7a00461ef6d91797a60b606367f6e344d upstream.

'clk' is copied to a userland with padding byte(s) after 'vclk_post_div'
field unitialized, leaking data from the stack. Fix this ensuring all of
'clk' is initialized to zero.

References: https://github.com/torvalds/linux/pull/441
Reported-by: sohu0106 <sohu0106@....com>
Signed-off-by: Vladis Dronov <vdronov@...hat.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/video/aty/atyfb_base.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -1852,7 +1852,7 @@ static int atyfb_ioctl(struct fb_info *i
 #if defined(DEBUG) && defined(CONFIG_FB_ATY_CT)
 	case ATYIO_CLKR:
 		if (M64_HAS(INTEGRATED)) {
-			struct atyclk clk;
+			struct atyclk clk = { 0 };
 			union aty_pll *pll = &par->pll;
 			u32 dsp_config = pll->ct.dsp_config;
 			u32 dsp_on_off = pll->ct.dsp_on_off;