Commit: efa73f1334e339902993bb4894da47242f0c4173 - linux_3.x_apsh4a0a (git)

linux-3.0.x for AP-SH4A-0A Board

Commit MetaInfo

• Revision: efa73f1334e339902993bb4894da47242f0c4173 (tree)
• Time: 2011-08-05 13:58:31
• Author: Tobias Klauser <tklauser@dist...>
• Commiter: Greg Kroah-Hartman

Log Message

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

commit 8547d4cc2b616e4f1dafebe2c673fc986422b506 upstream.

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 <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Change Summary

• modified: drivers/staging/usbip/vhci_hcd.c

Incremental Difference

--- a/drivers/staging/usbip/vhci_hcd.c
+++ b/drivers/staging/usbip/vhci_hcd.c
@@ -846,9 +846,9 @@ 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");