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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Vlad Tsyrklevich <vlad@tsyrklevich.net>,
        Kees Cook <keescook@chromium.org>, security@kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: [PATCH 4.20 072/111] omap2fb: Fix stack memory disclosure
Date:   Mon, 21 Jan 2019 14:43:06 +0100
Message-Id: <20190121122504.399319161@linuxfoundation.org>
In-Reply-To: <20190121122455.819406896@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

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

From: Vlad Tsyrklevich <vlad@tsyrklevich.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@tsyrklevich.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Fixes: b39a982ddecf ("OMAP: DSS2: omapfb driver")
Cc: security@kernel.org
[b.zolnierkie: prefix patch subject with "omap2fb: "]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -609,6 +609,8 @@ 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");