linux-kernel - [PATCH 3/4] GPU-DRM-TILCDC: Less function calls in tilcdc_convert_slave

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Date:   Thu, 22 Sep 2016 10:33:29 +0200
From:   SF Markus Elfring <elfring@...rs.sourceforge.net>
To:     dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        Jyri Sarha <jsarha@...com>,
        Tomi Valkeinen <tomi.valkeinen@...com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>
Subject: [PATCH 3/4] GPU-DRM-TILCDC: Less function calls in
 tilcdc_convert_slave_node() after error detection

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Thu, 22 Sep 2016 10:06:50 +0200

The of_node_put() function was called in some cases
by the tilcdc_convert_slave_node() function during error handling
even if the passed variable contained a null pointer.

* Adjust jump targets according to the Linux coding style convention.

* Split a condition check for resource detection failures so that
  each pointer from these function calls will be checked immediately.

  See also background information:
  Topic "CWE-754: Improper check for unusual or exceptional conditions"
  Link: https://cwe.mitre.org/data/definitions/754.html

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c b/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
index 6204405..6ee5865 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_slave_compat.c
@@ -209,25 +209,27 @@ void __init tilcdc_convert_slave_node(void)
 		return;
 
 	lcdc = of_find_matching_node(NULL, tilcdc_of_match);
-	slave = of_find_matching_node(NULL, tilcdc_slave_of_match);
+	if (!of_device_is_available(lcdc))
+		goto free_table;
 
-	if (!slave || !of_device_is_available(lcdc))
-		goto out;
+	slave = of_find_matching_node(NULL, tilcdc_slave_of_match);
+	if (!slave)
+		goto put_node_lcdc;
 
 	i2c = of_parse_phandle(slave, "i2c", 0);
 	if (!i2c) {
 		pr_err("%s: Can't find i2c node trough phandle\n", __func__);
-		goto out;
+		goto put_node_slave;
 	}
 
 	overlay = tilcdc_get_overlay(&kft);
 	if (!overlay)
-		goto out;
+		goto put_node_i2c;
 
 	encoder = of_find_matching_node(overlay, tilcdc_tda998x_of_match);
 	if (!encoder) {
 		pr_err("%s: Failed to find tda998x node\n", __func__);
-		goto out;
+		goto put_node_i2c;
 	}
 
 	tilcdc_copy_props(slave, encoder, tilcdc_slave_props, &kft);
@@ -238,10 +240,10 @@ void __init tilcdc_convert_slave_node(void)
 			continue;
 		if (!strncmp("i2c", (char *)prop->value, prop->length))
 			if (tilcdc_prop_str_update(prop, i2c->full_name, &kft))
-				goto out;
+				goto put_node_fragment;
 		if (!strncmp("lcdc", (char *)prop->value, prop->length))
 			if (tilcdc_prop_str_update(prop, lcdc->full_name, &kft))
-				goto out;
+				goto put_node_fragment;
 	}
 
 	tilcdc_node_disable(slave);
@@ -252,12 +254,16 @@ void __init tilcdc_convert_slave_node(void)
 	else
 		pr_info("%s: ti,tilcdc,slave node successfully converted\n",
 			__func__);
-out:
-	kfree_table_free(&kft);
+ put_node_fragment:
+	of_node_put(fragment);
+ put_node_i2c:
 	of_node_put(i2c);
+ put_node_slave:
 	of_node_put(slave);
+ put_node_lcdc:
 	of_node_put(lcdc);
-	of_node_put(fragment);
+ free_table:
+	kfree_table_free(&kft);
 }
 
 int __init tilcdc_slave_compat_init(void)
-- 
2.10.0