linux/process: Support reading empty values from /proc/pid/status

The file /proc/<pid>/status provides information about a process in
the format 'key: value'. The parsing of this file failed if 'value'
was empty.

Add an dummy value that will be taken in case the real value from
the status file does not exist.

Additionally, update the log message from the parsing code to also
output the exception, if one is raised.

Related: cuckoosandbox#3035

cuckoo/data/analyzer/linux/lib/api/process.py

@@ -31,10 +31,10 @@ def get_parent_pid(self):
     def get_proc_status(self):
         try:
             status = open("/proc/%u/status" % self.pid).readlines()
-            status_values = dict((i[0], i[1]) for i in [j.strip().split(None, 1) for j in status])
+            status_values = dict((i[0], i[1]) for i in [j.strip().split(None, 1) + [""] for j in status])
             return status_values
         except:
-            log.critical("could not get process status for pid %u", self.pid)
+            log.exception("could not get process status for pid %u", self.pid)
         return {}
 
     def execute(self, cmd):