From 63f1e05f7fe9ca509c60154d6a833abf96eecdc9 Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <garsilva@embeddedor.com>
Date: Wed, 6 Dec 2017 14:20:15 -0600
Subject: [PATCH] PM / devfreq: Fix potential NULL pointer dereference in governor_store
Git-commit: 63f1e05f7fe9ca509c60154d6a833abf96eecdc9
Patch-mainline: v4.16-rc1
References: bsc#1051510

df->governor is being dereferenced before it is null checked,
hence there is a potential null pointer dereference.

Notice that df->governor is being null checked at line 1004:
if (df->governor) {, which implies it might be null.

Fix this by null checking df->governor before dereferencing it.

Addresses-coverity-id: 1401988 ("Dereference before null check")
Fixes: bcf23c79c4e4 ("PM / devfreq: Fix available_governor sysfs")
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/devfreq/devfreq.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -935,7 +935,8 @@ static ssize_t governor_store(struct dev
 	if (df->governor == governor) {
 		ret = 0;
 		goto out;
-	} else if (df->governor->immutable || governor->immutable) {
+	} else if ((df->governor && df->governor->immutable) ||
+					governor->immutable) {
 		ret = -EINVAL;
 		goto out;
 	}