From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934116AbbCDGbP (ORCPT ); Wed, 4 Mar 2015 01:31:15 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:43912 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933825AbbCDGV4 (ORCPT ); Wed, 4 Mar 2015 01:21:56 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Gongbae Park , Matthias Brugger , Daniel Lezcano Subject: [PATCH 3.19 154/175] clocksource: mtk: Fix race conditions in probe code Date: Tue, 3 Mar 2015 22:15:32 -0800 Message-Id: <20150304061051.391002141@linuxfoundation.org> X-Mailer: git-send-email 2.3.1 In-Reply-To: <20150304061026.134125919@linuxfoundation.org> References: <20150304061026.134125919@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthias Brugger commit d4a19eb3b15a4ba98f627182f48d5bc0cffae670 upstream. We have two race conditions in the probe code which could lead to a null pointer dereference in the interrupt handler. The interrupt handler accesses the clockevent device, which may not yet be registered. First race condition happens when the interrupt handler gets registered before the interrupts get disabled. The second race condition happens when the interrupts get enabled, but the clockevent device is not yet registered. Fix that by disabling the interrupts before we register the interrupt and enable the interrupts after the clockevent device got registered. Reported-by: Gongbae Park Signed-off-by: Matthias Brugger Signed-off-by: Daniel Lezcano Signed-off-by: Greg Kroah-Hartman --- drivers/clocksource/mtk_timer.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/drivers/clocksource/mtk_timer.c +++ b/drivers/clocksource/mtk_timer.c @@ -224,6 +224,8 @@ static void __init mtk_timer_init(struct } rate = clk_get_rate(clk); + mtk_timer_global_reset(evt); + if (request_irq(evt->dev.irq, mtk_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL, "mtk_timer", evt)) { pr_warn("failed to setup irq %d\n", evt->dev.irq); @@ -232,8 +234,6 @@ static void __init mtk_timer_init(struct evt->ticks_per_jiffy = DIV_ROUND_UP(rate, HZ); - mtk_timer_global_reset(evt); - /* Configure clock source */ mtk_timer_setup(evt, GPT_CLK_SRC, TIMER_CTRL_OP_FREERUN); clocksource_mmio_init(evt->gpt_base + TIMER_CNT_REG(GPT_CLK_SRC), @@ -241,10 +241,11 @@ static void __init mtk_timer_init(struct /* Configure clock event */ mtk_timer_setup(evt, GPT_CLK_EVT, TIMER_CTRL_OP_REPEAT); - mtk_timer_enable_irq(evt, GPT_CLK_EVT); - clockevents_config_and_register(&evt->dev, rate, 0x3, 0xffffffff); + + mtk_timer_enable_irq(evt, GPT_CLK_EVT); + return; err_clk_disable: