[PATCH 2/7] tracing/filters: fix NULL pointer dereference

[Li Zefan <lizf@cn.fujitsu.com>]

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>
---
 kernel/trace/trace_events_filter.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 026be41..9d2162f 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;
-- 
1.5.4.rc3