[PATCH 3.16 105/136] USB: serial: whiteheat: fix potential slab corruption

[Ben Hutchings]

3.16.80-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit 1251dab9e0a2c4d0d2d48370ba5baa095a5e8774 upstream.

Fix a user-controlled slab buffer overflow due to a missing sanity check
on the bulk-out transfer buffer used for control requests.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20191029102354.2733-2-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/usb/serial/whiteheat.c | 4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -604,6 +604,10 @@ static int firm_send_command(struct usb_
 
 	command_port = port->serial->port[COMMAND_PORT];
 	command_info = usb_get_serial_port_data(command_port);
+
+	if (command_port->bulk_out_size < datasize + 1)
+		return -EIO;
+
 	mutex_lock(&command_info->mutex);
 	command_info->command_finished = false;