Commit 8547d4cc authored by Tobias Klauser's avatar Tobias Klauser Committed by Greg Kroah-Hartman

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: default avatarTobias Klauser <tklauser@distanz.ch>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent c88f9906
......@@ -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");
......
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