linux-kernel - [PATCH 3.16 033/202] omap2fb: Fix stack memory disclosure

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Date:   Sat, 27 Apr 2019 16:13:09 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Kees Cook" <keescook@...omium.org>, security@...nel.org,
        "Bartlomiej Zolnierkiewicz" <b.zolnierkie@...sung.com>,
        "Vlad Tsyrklevich" <vlad@...rklevich.net>
Subject: [PATCH 3.16 033/202] omap2fb: Fix stack memory disclosure

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

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

From: Vlad Tsyrklevich <vlad@...rklevich.net>

commit a01421e4484327fe44f8e126793ed5a48a221e24 upstream.

Using [1] for static analysis I found that the OMAPFB_QUERY_PLANE,
OMAPFB_GET_COLOR_KEY, OMAPFB_GET_DISPLAY_INFO, and OMAPFB_GET_VRAM_INFO
cases could all leak uninitialized stack memory--either due to
uninitialized padding or 'reserved' fields.

Fix them by clearing the shared union used to store copied out data.

[1] https://github.com/vlad902/kernel-uninitialized-memory-checker

Signed-off-by: Vlad Tsyrklevich <vlad@...rklevich.net>
Reviewed-by: Kees Cook <keescook@...omium.org>
Fixes: b39a982ddecf ("OMAP: DSS2: omapfb driver")
Cc: security@...nel.org
[b.zolnierkie: prefix patch subject with "omap2fb: "]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c | 2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c
+++ b/drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c
@@ -606,6 +606,8 @@ int omapfb_ioctl(struct fb_info *fbi, un
 
 	int r = 0;
 
+	memset(&p, 0, sizeof(p));
+
 	switch (cmd) {
 	case OMAPFB_SYNC_GFX:
 		DBG("ioctl SYNC_GFX\n");