diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2013-07-26 19:25:36 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-07-29 22:05:40 -0400 |
| commit | bc6f6b08dee5645770efb4b76186ded313f23752 (patch) | |
| tree | 4f2a94646a39b8454e21bed38f093f73c8752345 | |
| parent | 1a11126bcb7c93c289bf3218fa546fd3b0c0df8b (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.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index c2d13c528c3..3dfa8419d0d 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; |