From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751864Ab2HDECE (ORCPT ); Sat, 4 Aug 2012 00:02:04 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:45263 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751001Ab2HDEB5 (ORCPT ); Sat, 4 Aug 2012 00:01:57 -0400 From: Ming Lei To: Linus Torvalds , Greg Kroah-Hartman Cc: "Rafael J. Wysocki" , Borislav Petkov , linux-kernel@vger.kernel.org, Ming Lei Subject: [RFC PATCH v1 02/15] firmware loader: fix races during loading firmware Date: Sat, 4 Aug 2012 12:01:17 +0800 Message-Id: <1344052890-31935-3-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1344052890-31935-1-git-send-email-ming.lei@canonical.com> References: <1344052890-31935-1-git-send-email-ming.lei@canonical.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch fixes two races in loading firmware: 1, FW_STATUS_DONE should be set before waking up the task waitting on _request_firmware_load, otherwise FW_STATUS_ABORT may be thought as DONE mistakenly. 2, Inside _request_firmware_load(), there is a small window between wait_for_completion() and mutex_lock(&fw_lock), and 'echo 1 > loading' still may happen during the period, so this patch checks FW_STATUS_DONE to prevent pages' buffer completed from being freed in firmware_loading_store. Signed-off-by: Ming Lei --- drivers/base/firmware_class.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c index 1cbefcf..1915ad8 100644 --- a/drivers/base/firmware_class.c +++ b/drivers/base/firmware_class.c @@ -243,18 +243,21 @@ static ssize_t firmware_loading_store(struct device *dev, switch (loading) { case 1: /* discarding any previous partial load */ - for (i = 0; i < fw_priv->nr_pages; i++) - __free_page(fw_priv->pages[i]); - kfree(fw_priv->pages); - fw_priv->pages = NULL; - fw_priv->page_array_size = 0; - fw_priv->nr_pages = 0; - set_bit(FW_STATUS_LOADING, &fw_priv->status); + if (!test_bit(FW_STATUS_DONE, &fw_priv->status)) { + for (i = 0; i < fw_priv->nr_pages; i++) + __free_page(fw_priv->pages[i]); + kfree(fw_priv->pages); + fw_priv->pages = NULL; + fw_priv->page_array_size = 0; + fw_priv->nr_pages = 0; + set_bit(FW_STATUS_LOADING, &fw_priv->status); + } break; case 0: if (test_bit(FW_STATUS_LOADING, &fw_priv->status)) { - complete(&fw_priv->completion); + set_bit(FW_STATUS_DONE, &fw_priv->status); clear_bit(FW_STATUS_LOADING, &fw_priv->status); + complete(&fw_priv->completion); break; } /* fallthrough */ @@ -557,7 +560,6 @@ static int _request_firmware_load(struct firmware_priv *fw_priv, bool uevent, wait_for_completion(&fw_priv->completion); - set_bit(FW_STATUS_DONE, &fw_priv->status); del_timer_sync(&fw_priv->timeout); mutex_lock(&fw_lock); -- 1.7.9.5