Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit b507cc97 authored by Pete Zaitcev's avatar Pete Zaitcev Committed by Greg Kroah-Hartman
Browse files

USB: fix usb-serial generic recursive lock 

Nobody should be using the generic usb-serial for anything other than
testing. Still, it's not a good thing that it's easy to lock up. There
is a traceback from NMI oopser here:
 https://bugzilla.redhat.com/show_bug.cgi?id=431379



But in short, if a line discipline has a chance to echo anything, input
can loop back a write method. So, don't call tty_flip_buffer_push from
under a lock taken on write path.

Signed-off-by: default avatarPete Zaitcev <zaitcev@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent cdeeeae0

drivers/usb/serial/generic.c

+6 −4
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ static void flush_and_resubmit_read_urb (struct usb_serial_port *port) 
		room = tty_buffer_request_room(tty, urb->actual_length);

		if (room) {

			tty_insert_flip_string(tty, urb->transfer_buffer, room);

			tty_flip_buffer_push(tty); /* is this allowed from an URB callback ? */

			tty_flip_buffer_push(tty);

		}

	}
@@ -349,11 +349,13 @@ void usb_serial_generic_read_bulk_callback (struct urb *urb) 


	/* Throttle the device if requested by tty */

	spin_lock_irqsave(&port->lock, flags);

	if (!(port->throttled = port->throttle_req))

		/* Handle data and continue reading from device */

	if (!(port->throttled = port->throttle_req)) {

		spin_unlock_irqrestore(&port->lock, flags);

		flush_and_resubmit_read_urb(port);

	} else {

		spin_unlock_irqrestore(&port->lock, flags);

	}

}

EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);



void usb_serial_generic_write_bulk_callback (struct urb *urb)