Commit ae98d27a authored Feb 02, 2017 by Steven Rostedt (VMware)

ftrace: Have set_graph_functions handle write with RDWR



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.

Acked-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

parent d4ad9a1c

kernel/trace/ftrace.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -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))) {