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From:   Gaurav Singh <gaurav1086@gmail.com>
To:     gaurav1086@gmail.com, Shuah Khan <shuah@kernel.org>,
        Tejun Heo <tj@kernel.org>,
        =?UTF-8?q?Michal=20Koutn=C3=BD?= <mkoutny@suse.com>,
        Roman Gushchin <guro@fb.com>,
        Chris Down <chris@chrisdown.name>,
        Andrew Morton <akpm@linux-foundation.org>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        linux-kselftest@vger.kernel.org (open list:KERNEL SELFTEST FRAMEWORK),
        linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] [cgroup/testing] cg_read_strcmp: Fix null pointer dereference
Date:   Sat, 25 Jul 2020 14:14:51 -0400
Message-Id: <20200725181506.20199-1-gaurav1086@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Passing NULL in strcmp will cause a segmentation fault.
Fix this by returning -1 if expected is NULL pointer. 

Signed-off-by: Gaurav Singh <gaurav1086@gmail.com>
---
 tools/testing/selftests/cgroup/cgroup_util.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index 8a637ca7d73a..05853b0b8831 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -106,7 +106,7 @@ int cg_read_strcmp(const char *cgroup, const char *control,
 
 	/* Handle the case of comparing against empty string */
 	if (!expected)
-		size = 32;
+		return -1;
 	else
 		size = strlen(expected) + 1;
 
-- 
2.17.1