cgroup: fix dereference before null check

Coverity: 1230177 Dereference before null check

There may be a null pointer dereference, or else the comparison against
null is unnecessary.  In parse_task_cgroup: All paths that lead to this
null pointer comparison already dereference the pointer earlier
(CWE-476)

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

proc_parse.c

@@ -1598,7 +1598,8 @@ int parse_task_cgroup(int pid, struct list_head *retl, unsigned int *n)
 		 * 2:name=systemd:/user.slice/user-1000.slice/session-1.scope
 		 */
 		name = strchr(buf, ':') + 1;
-		path = strchr(name, ':');
+		if (name)
+			path = strchr(name, ':');
 		if (!name || !path) {
 			pr_err("Failed parsing cgroup %s\n", buf);
 			xfree(ncc);