tracing/filters: fix NULL pointer dereference

Try this, and you'll see NULL pointer dereference bug:

  # echo -n 'parent_comm ==' > sched/sched_process_fork/filter

Because we passed NULL ptr to simple_strtoull().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04C43.1050504@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 026be412f356..9d2162fd2305 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -410,6 +410,11 @@ int filter_parse(char **pbuf, struct filter_pred *pred)
                 }
         }
 
+        if (!val_str) {
+                pred->field_name = NULL;
+                return -EINVAL;
+        }
+
         pred->field_name = kstrdup(pred->field_name, GFP_KERNEL);
         if (!pred->field_name)
                 return -ENOMEM;