From: Tobias Wolf <dev-NTEO@vplace.de>
Date: Wed, 23 Nov 2016 09:40:07 +0000 (+0100)
Subject: of: Add check to of_scan_flat_dt() before accessing initial_boot_params
X-Git-Tag: archive/raspbian/4.9.30-2+deb9u2+rpi1~4^2~257
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success/%22http:/www.example.com/cgi/success?a=commitdiff_plain;h=a4f9453542385d8e5e40dd71c00cc0d3a8a3a12e;p=linux-4.9.git

of: Add check to of_scan_flat_dt() before accessing initial_boot_params

commit 3ec754410cb3e931a6c4920b1a150f21a94a2bf4 upstream.

An empty __dtb_start to __dtb_end section might result in
initial_boot_params being null for arch/mips/ralink. This showed that the
boot process hangs indefinitely in of_scan_flat_dt().

Signed-off-by: Tobias Wolf <dev-NTEO@vplace.de>
Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14605/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 6a43fd3d0576..502f5547a1f2 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -741,9 +741,12 @@ int __init of_scan_flat_dt(int (*it)(unsigned long node,
 	const char *pathp;
 	int offset, rc = 0, depth = -1;
 
-        for (offset = fdt_next_node(blob, -1, &depth);
-             offset >= 0 && depth >= 0 && !rc;
-             offset = fdt_next_node(blob, offset, &depth)) {
+	if (!blob)
+		return 0;
+
+	for (offset = fdt_next_node(blob, -1, &depth);
+	     offset >= 0 && depth >= 0 && !rc;
+	     offset = fdt_next_node(blob, offset, &depth)) {
 
 		pathp = fdt_get_name(blob, offset, NULL);
 		if (*pathp == '/')