From 33c920f7c5952dfc42d1b8ea6efe16b1f0bb0c5b Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Fri, 21 Aug 2026 17:45:43 +0200 Subject: [PATCH] USB: serial: fix port tear down use-after-free Some drivers for multiport devices access port driver data from completion handlers of shared URBs submitted at attach() or first open() and stopped at disconnect() or last close(), respectively. A simple NULL check before accessing the driver data makes sure that a port state container has at least been allocated, but a completion handler can still race with port tear down. Reorder the disconnect handling so that ports are not deregistered (and their driver data freed) until after all ports have been hung up and the driver disconnect() callback has run so that all I/O has been stopped. Fixes: 2d93148ab698 ("USB: serial: fix lifetime and locking problems") Reported-by: syzbot+e5e28c3e953b2eebb16e@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/6a7e6fb9.ec5dc6cc.21cb3f.00c0.GAE@google.com/ Cc: stable@vger.kernel.org # 2.6.30 Cc: Alan Stern Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold --- drivers/usb/serial/usb-serial.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 17edc057a311..a4fbc849c0fa 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -1191,11 +1191,16 @@ static void usb_serial_disconnect(struct usb_interface *interface) usb_serial_port_poison_urbs(port); wake_up_interruptible(&port->port.delta_msr_wait); cancel_work_sync(&port->work); + } + + if (serial->type->disconnect) + serial->type->disconnect(serial); + + for (i = 0; i < serial->num_ports; ++i) { + port = serial->port[i]; if (device_is_registered(&port->dev)) device_del(&port->dev); } - if (serial->type->disconnect) - serial->type->disconnect(serial); release_sibling(serial, interface);