From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756162Ab1HCXpE (ORCPT ); Wed, 3 Aug 2011 19:45:04 -0400 Received: from cantor2.suse.de ([195.135.220.15]:33388 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755950Ab1HCX0D (ORCPT ); Wed, 3 Aug 2011 19:26:03 -0400 X-Mailbox-Line: From gregkh@clark.kroah.org Wed Aug 3 15:12:44 2011 Message-Id: <20110803221244.694847938@clark.kroah.org> User-Agent: quilt/0.48-16.4 Date: Wed, 03 Aug 2011 15:00:26 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Tobias Klauser Subject: [006/102] Staging: usbip: vhci-hcd: Do not kill already dead RX/TX kthread In-Reply-To: <20110803221345.GA10346@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let us know. ------------------ From: Tobias Klauser 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 Signed-off-by: Greg Kroah-Hartman --- drivers/staging/usbip/vhci_hcd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/staging/usbip/vhci_hcd.c +++ b/drivers/staging/usbip/vhci_hcd.c @@ -846,9 +846,9 @@ static void vhci_shutdown_connection(str } /* 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");