Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030764AbaGCKFv (ORCPT ); Thu, 3 Jul 2014 06:05:51 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51771 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758405AbaGCJWU (ORCPT ); Thu, 3 Jul 2014 05:22:20 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Johan Hovold , Greg Kroah-Hartman , Luis Henriques Subject: [PATCH 3.11 065/198] USB: cdc-acm: fix write and suspend race Date: Thu, 3 Jul 2014 10:18:28 +0100 Message-Id: <1404379241-8590-66-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> References: <1404379241-8590-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.13 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit 5a345c20c17d87099224a4be12e69e5bd7023dca upstream. Fix race between write() and suspend() which could lead to writes being dropped (or I/O while suspended) if the device is runtime suspended while a write request is being processed. Specifically, suspend() releases the write_lock after determining the device is idle but before incrementing the susp_count, thus leaving a window where a concurrent write() can submit an urb. Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices that support remote wakeup") Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman Signed-off-by: Luis Henriques --- drivers/usb/class/cdc-acm.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 8b8236fd24cf..6ebcd38dfb06 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1420,18 +1420,15 @@ static int acm_suspend(struct usb_interface *intf, pm_message_t message) struct acm *acm = usb_get_intfdata(intf); int cnt; + spin_lock_irq(&acm->read_lock); + spin_lock(&acm->write_lock); if (PMSG_IS_AUTO(message)) { - int b; - - spin_lock_irq(&acm->write_lock); - b = acm->transmitting; - spin_unlock_irq(&acm->write_lock); - if (b) + if (acm->transmitting) { + spin_unlock(&acm->write_lock); + spin_unlock_irq(&acm->read_lock); return -EBUSY; + } } - - spin_lock_irq(&acm->read_lock); - spin_lock(&acm->write_lock); cnt = acm->susp_count++; spin_unlock(&acm->write_lock); spin_unlock_irq(&acm->read_lock); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/