From: "Steven Rostedt (VMware)" <[email protected]> Since reading the set_graph_functions uses seq functions, which sets the file->private_data pointer to a seq_file descriptor. On writes the ftrace_graph_data descriptor is set to file->private_data. But if the file is opened for RDWR, the ftrace_graph_write() will incorrectly use the file->private_data descriptor instead of ((struct seq_file *)file->private_data)->private pointer, and this can crash the kernel.
Signed-off-by: Steven Rostedt (VMware) <[email protected]> --- kernel/trace/ftrace.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b7df0dcf8652..0233c8cb45f4 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4842,6 +4842,12 @@ ftrace_graph_write(struct file *file, const char __user *ubuf, if (trace_parser_get_init(&parser, FTRACE_BUFF_MAX)) return -ENOMEM; + /* Read mode uses seq functions */ + if (file->f_mode & FMODE_READ) { + struct seq_file *m = file->private_data; + fgd = m->private; + } + read = trace_get_user(&parser, ubuf, cnt, ppos); if (read >= 0 && trace_parser_loaded((&parser))) { -- 2.10.2
