ftrace: Have set_graph_functions handle write with RDWR
authorSteven Rostedt (VMware) <rostedt@goodmis.org>
Thu, 2 Feb 2017 21:59:06 +0000 (16:59 -0500)
committerSteven Rostedt (VMware) <rostedt@goodmis.org>
Fri, 3 Feb 2017 15:59:23 +0000 (10:59 -0500)
commitae98d27afc3bde5a48f440d905317602a5cfb0d2
tree8b49f804b55c771a3e8f106438551fa79a700939
parentd4ad9a1ccac31a04a32b5e7547b70428830e0218
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>
kernel/trace/ftrace.c