From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2993565AbcKQK5k (ORCPT ); Thu, 17 Nov 2016 05:57:40 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:47614 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932250AbcKQKgg (ORCPT ); Thu, 17 Nov 2016 05:36:36 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maxime Ripard , Chen-Yu Tsai , linux-sunxi@googlegroups.com, Daniel Lezcano , linux-arm-kernel@lists.infradead.org, Thomas Gleixner Subject: [PATCH 4.8 65/92] Revert "clocksource/drivers/timer_sun5i: Replace code by clocksource_mmio_init" Date: Thu, 17 Nov 2016 11:32:38 +0100 Message-Id: <20161117103227.073195108@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161117103224.218007793@linuxfoundation.org> References: <20161117103224.218007793@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chen-Yu Tsai commit 593876838826914a7e4e05fbbcb728be6fbc4d89 upstream. struct clocksource is also used by the clk notifier callback, to unregister and re-register the clocksource with a different clock rate. clocksource_mmio_init does not pass back a pointer to the struct used, and the clk notifier callback assumes that the struct clocksource in struct sun5i_timer_clksrc is valid. This results in a kernel NULL pointer dereference when the hstimer clock is changed: Unable to handle kernel NULL pointer dereference at virtual address 00000004 [] (clocksource_unbind) from [] (clocksource_unregister+0x2c/0x44) [] (clocksource_unregister) from [] (sun5i_rate_cb_clksrc+0x34/0x3c) [] (sun5i_rate_cb_clksrc) from [] (notifier_call_chain+0x44/0x84) [] (notifier_call_chain) from [] (__srcu_notifier_call_chain+0x44/0x60) [] (__srcu_notifier_call_chain) from [] (srcu_notifier_call_chain+0x18/0x20) [] (srcu_notifier_call_chain) from [] (__clk_notify+0x70/0x7c) [] (__clk_notify) from [] (clk_propagate_rate_change+0xa4/0xc4) [] (clk_propagate_rate_change) from [] (clk_propagate_rate_change+0x6c/0xc4) Revert the commit for now. clocksource_mmio_init can be made to pass back a pointer, but the code churn and usage of an inner struct might not be worth it. Fixes: 157dfadef832 ("clocksource/drivers/timer_sun5i: Replace code by clocksource_mmio_init") Reported-by: Maxime Ripard Signed-off-by: Chen-Yu Tsai Cc: linux-sunxi@googlegroups.com Cc: Daniel Lezcano Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/20161018054918.26855-1-wens@csie.org Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- drivers/clocksource/timer-sun5i.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/drivers/clocksource/timer-sun5i.c +++ b/drivers/clocksource/timer-sun5i.c @@ -152,6 +152,13 @@ static irqreturn_t sun5i_timer_interrupt return IRQ_HANDLED; } +static cycle_t sun5i_clksrc_read(struct clocksource *clksrc) +{ + struct sun5i_timer_clksrc *cs = to_sun5i_timer_clksrc(clksrc); + + return ~readl(cs->timer.base + TIMER_CNTVAL_LO_REG(1)); +} + static int sun5i_rate_cb_clksrc(struct notifier_block *nb, unsigned long event, void *data) { @@ -210,8 +217,13 @@ static int __init sun5i_setup_clocksourc writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD, base + TIMER_CTL_REG(1)); - ret = clocksource_mmio_init(base + TIMER_CNTVAL_LO_REG(1), node->name, - rate, 340, 32, clocksource_mmio_readl_down); + cs->clksrc.name = node->name; + cs->clksrc.rating = 340; + cs->clksrc.read = sun5i_clksrc_read; + cs->clksrc.mask = CLOCKSOURCE_MASK(32); + cs->clksrc.flags = CLOCK_SOURCE_IS_CONTINUOUS; + + ret = clocksource_register_hz(&cs->clksrc, rate); if (ret) { pr_err("Couldn't register clock source.\n"); goto err_remove_notifier;