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

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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>
This commit is contained in:
Tobias Klauser 2011-06-24 15:48:47 +02:00 committed by Greg Kroah-Hartman
parent c88f9906c3
commit 8547d4cc2b
1 changed files with 2 additions and 2 deletions
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4
drivers/staging/usbip/vhci_hcd.c
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@ -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");