perf traceevent: Ensure read cmdlines are null terminated.

Issue detected by address sanitizer.

Fixes: cd4ceb6 ("perf util: Save pid-cmdline mapping into tracing header")
Signed-off-by: Ian Rogers <[email protected]>
Acked-by: Namhyung Kim <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lore.kernel.org/lkml/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Author: captain5050

tools/perf/util/trace-event-read.c

@@ -361,6 +361,7 @@ static int read_saved_cmdline(struct tep_handle *pevent)
 		pr_debug("error reading saved cmdlines\n");
 		goto out;
 	}
+	buf[ret] = '\0';
 
 	parse_saved_cmdline(pevent, buf, size);
 	ret = 0;