Commit 8547d4cc authored Jun 24, 2011 by Tobias Klauser Committed by Greg Kroah-Hartman Jul 05, 2011

Staging: usbip: vhci-hcd: Do not kill already dead RX/TX kthread



When unbinding a device on the host which was still attached on the
client, I got a NULL pointer dereference on the client. This turned out
to be due to kthread_stop() being called on an already dead kthread.

Here is how I was able to reproduce the problem:

 server:# usbip bind -b 1-2
                                client:# usbip attach -h server -b 1-2
 server:# usbip unbind -b 1-2

This patch fixes the problem by checking the kthread before attempting
to kill it, as it is done on the opposite side in
stub_shutdown_connection().

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent c88f9906

drivers/staging/usbip/vhci_hcd.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -860,9 +860,9 @@ static void vhci_shutdown_connection(struct usbip_device *ud)
		}

		/* kill threads related to this sdev, if v.c. exists */
		if (vdev->ud.tcp_rx)
		if (vdev->ud.tcp_rx && !task_is_dead(vdev->ud.tcp_rx))
		kthread_stop(vdev->ud.tcp_rx);
		if (vdev->ud.tcp_tx)
		if (vdev->ud.tcp_tx && !task_is_dead(vdev->ud.tcp_tx))
		kthread_stop(vdev->ud.tcp_tx);

		pr_info("stop threads\n");