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authorOleg Nesterov <oleg@redhat.com>2013-07-26 19:25:36 +0200
committerSteven Rostedt <rostedt@goodmis.org>2013-07-29 22:05:40 -0400
commitbc6f6b08dee5645770efb4b76186ded313f23752 (patch)
tree4f2a94646a39b8454e21bed38f093f73c8752345
parent1a11126bcb7c93c289bf3218fa546fd3b0c0df8b (diff)
tracing: Change event_enable/disable_read() to verify i_private != NULL
tracing_open_generic_file() is racy, ftrace_event_file can be already freed by rmdir or trace_remove_event_call(). Change event_enable_read() and event_disable_read() to read and verify "file = i_private" under event_mutex. This fixes nothing, but now we can change debugfs_remove("enable") callers to nullify ->i_private and fix the the problem. Link: http://lkml.kernel.org/r/20130726172536.GA3612@redhat.com Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace_events.c30
1 files changed, 20 insertions, 10 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index c2d13c528c3c..3dfa8419d0dc 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -684,15 +684,25 @@ static ssize_t
event_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
loff_t *ppos)
{
- struct ftrace_event_file *file = filp->private_data;
+ struct ftrace_event_file *file;
+ unsigned long flags;
char buf[4] = "0";
- if (file->flags & FTRACE_EVENT_FL_ENABLED &&
- !(file->flags & FTRACE_EVENT_FL_SOFT_DISABLED))
+ mutex_lock(&event_mutex);
+ file = event_file_data(filp);
+ if (likely(file))
+ flags = file->flags;
+ mutex_unlock(&event_mutex);
+
+ if (!file)
+ return -ENODEV;
+
+ if (flags & FTRACE_EVENT_FL_ENABLED &&
+ !(flags & FTRACE_EVENT_FL_SOFT_DISABLED))
strcpy(buf, "1");
- if (file->flags & FTRACE_EVENT_FL_SOFT_DISABLED ||
- file->flags & FTRACE_EVENT_FL_SOFT_MODE)
+ if (flags & FTRACE_EVENT_FL_SOFT_DISABLED ||
+ flags & FTRACE_EVENT_FL_SOFT_MODE)
strcat(buf, "*");
strcat(buf, "\n");
@@ -704,13 +714,10 @@ static ssize_t
event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
{
- struct ftrace_event_file *file = filp->private_data;
+ struct ftrace_event_file *file;
unsigned long val;
int ret;
- if (!file)
- return -EINVAL;
-
ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
if (ret)
return ret;
@@ -722,8 +729,11 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
switch (val) {
case 0:
case 1:
+ ret = -ENODEV;
mutex_lock(&event_mutex);
- ret = ftrace_event_enable_disable(file, val);
+ file = event_file_data(filp);
+ if (likely(file))
+ ret = ftrace_event_enable_disable(file, val);
mutex_unlock(&event_mutex);
break;