3.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Oleg Nesterov <[email protected]> commit c5a44a1200c6eda2202434f25325e8ad19533fca upstream. trace_format_open() and trace_format_seq_ops are racy, nothing protects ftrace_event_call from trace_remove_event_call(). Change f_start() to take event_mutex and verify i_private != NULL, change f_stop() to drop this lock. This fixes nothing, but now we can change debugfs_remove("format") callers to nullify ->i_private and fix the the problem. Note: the usage of event_mutex is sub-optimal but simple, we can change this later. Link: http://lkml.kernel.org/r/[email protected] Reviewed-by: Masami Hiramatsu <[email protected]> Signed-off-by: Oleg Nesterov <[email protected]> Signed-off-by: Steven Rostedt <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- kernel/trace/trace_events.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -838,7 +838,7 @@ enum { static void *f_next(struct seq_file *m, void *v, loff_t *pos) { - struct ftrace_event_call *call = m->private; + struct ftrace_event_call *call = event_file_data(m->private); struct ftrace_event_field *field; struct list_head *common_head = &ftrace_common_fields; struct list_head *head = trace_get_fields(call); @@ -882,6 +882,11 @@ static void *f_start(struct seq_file *m, loff_t l = 0; void *p; + /* ->stop() is called even if ->start() fails */ + mutex_lock(&event_mutex); + if (!event_file_data(m->private)) + return ERR_PTR(-ENODEV); + /* Start by showing the header */ if (!*pos) return (void *)FORMAT_HEADER; @@ -896,7 +901,7 @@ static void *f_start(struct seq_file *m, static int f_show(struct seq_file *m, void *v) { - struct ftrace_event_call *call = m->private; + struct ftrace_event_call *call = event_file_data(m->private); struct ftrace_event_field *field; const char *array_descriptor; @@ -947,6 +952,7 @@ static int f_show(struct seq_file *m, vo static void f_stop(struct seq_file *m, void *p) { + mutex_unlock(&event_mutex); } static const struct seq_operations trace_format_seq_ops = { @@ -958,7 +964,6 @@ static const struct seq_operations trace static int trace_format_open(struct inode *inode, struct file *file) { - struct ftrace_event_call *call = inode->i_private; struct seq_file *m; int ret; @@ -967,7 +972,7 @@ static int trace_format_open(struct inod return ret; m = file->private_data; - m->private = call; + m->private = file; return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
