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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,
        Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        Alexandre Belloni <alexandre.belloni@free-electrons.com>,
        Johan Hovold <johan@kernel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Subject: [PATCH 4.4 16/33] video: fbdev: atmel_lcdfb: fix display-timings lookup
Date:   Wed, 21 Feb 2018 13:44:59 +0100
Message-Id: <20180221124410.482540641@linuxfoundation.org>
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4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Johan Hovold <johan@kernel.org>

commit 9cb18db0701f6b74f0c45c23ad767b3ebebe37f6 upstream.

Fix child-node lookup during probe, which ended up searching the whole
device tree depth-first starting at the parent rather than just matching
on its children.

To make things worse, the parent display node was also prematurely
freed.

Note that the display and timings node references are never put after a
successful dt-initialisation so the nodes would leak on later probe
deferrals and on driver unbind.

Fixes: b985172b328a ("video: atmel_lcdfb: add device tree suport")
Cc: stable <stable@vger.kernel.org>     # 3.13
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/video/fbdev/atmel_lcdfb.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/video/fbdev/atmel_lcdfb.c
+++ b/drivers/video/fbdev/atmel_lcdfb.c
@@ -1120,7 +1120,7 @@ static int atmel_lcdfb_of_init(struct at
 		goto put_display_node;
 	}
 
-	timings_np = of_find_node_by_name(display_np, "display-timings");
+	timings_np = of_get_child_by_name(display_np, "display-timings");
 	if (!timings_np) {
 		dev_err(dev, "failed to find display-timings node\n");
 		ret = -ENODEV;
@@ -1141,6 +1141,12 @@ static int atmel_lcdfb_of_init(struct at
 		fb_add_videomode(&fb_vm, &info->modelist);
 	}
 
+	/*
+	 * FIXME: Make sure we are not referencing any fields in display_np
+	 * and timings_np and drop our references to them before returning to
+	 * avoid leaking the nodes on probe deferral and driver unbind.
+	 */
+
 	return 0;
 
 put_timings_node: