[PATCH 1/7] tracing/filters: NUL-terminate user input filter

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

Make sure messages from user space are NUL-terminated strings,
otherwise we could dump random memory while reading filter file.

Try this:
 # echo 'parent_comm ==' > events/sched/sched_process_fork/filter
 # cat events/sched/sched_process_fork/filter
 parent_comm == �

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/trace/trace_events.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 64ec4d2..054bc18 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -503,6 +503,7 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
+	buf[cnt] = '\0';
 
 	pred = kzalloc(sizeof(*pred), GFP_KERNEL);
 	if (!pred)
@@ -569,6 +570,7 @@ subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
+	buf[cnt] = '\0';
 
 	pred = kzalloc(sizeof(*pred), GFP_KERNEL);
 	if (!pred)
-- 
1.5.4.rc3