From: Gustavo A. R. Silva <garsilva@embeddedor.com>
Date: Wed, 6 Dec 2017 20:20:15 +0000 (-0600)
Subject: PM / devfreq: Fix potential NULL pointer dereference in governor_store
X-Git-Tag: v4.16-rc1~196^2^3^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=63f1e05f7fe9ca509c60154d6a833abf96eecdc9;p=thirdparty%2Fkernel%2Flinux.git

PM / devfreq: Fix potential NULL pointer dereference in governor_store

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>
---

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 99c4021fc33b0..fe2af6aa88fc2 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -996,7 +996,8 @@ static ssize_t governor_store(struct device *dev, struct device_attribute *attr,
 	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;
 	}