From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9709C38A02 for ; Mon, 31 Oct 2022 06:40:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229515AbiJaGk6 (ORCPT ); Mon, 31 Oct 2022 02:40:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55742 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229642AbiJaGk5 (ORCPT ); Mon, 31 Oct 2022 02:40:57 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADE327662 for ; Sun, 30 Oct 2022 23:40:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4AB8A60FDF for ; Mon, 31 Oct 2022 06:40:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B57BC433C1; Mon, 31 Oct 2022 06:40:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667198454; bh=lqMLB0TfOpzztaLAK9HMkaiFOchkledx/zD7bI4QFog=; h=Subject:To:Cc:From:Date:From; b=yZbV0rtmWz0OuWKEdd5zCvBB1E50R1vfEn22ZZgl9nmVa+TR9A4qz+byAjb21V+Ry x1UFaG+VHIei63yHXWYkhgV3G/HC3ijOqEjxkAsQrSdOIgyo7168Xx7kdi+5+Qwczt 8GI5BM2ZECOq4E8i6paAfZEcbLZU/XzDw774fKSg= Subject: FAILED: patch "[PATCH] counter: 104-quad-8: Fix race getting function mode and" failed to apply to 5.15-stable tree To: william.gray@linaro.org Cc: From: Date: Mon, 31 Oct 2022 07:41:50 +0100 Message-ID: <166719851012451@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . Possible dependencies: d501d37841d3 ("counter: 104-quad-8: Fix race getting function mode and direction") aea8334b24fe ("counter: 104-quad-8: Convert to counter_priv() wrapper") 7aa2ba0df651 ("counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8") 09db4678bfbb ("counter: 104-quad-8: Replace mutex with spinlock") aaec1a0f76ec ("counter: Internalize sysfs interface code") ea434ff82649 ("counter: stm32-timer-cnt: Provide defines for slave mode selection") 05593a3fd103 ("counter: stm32-lptimer-cnt: Provide defines for clock polarities") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d501d37841d3b7f18402d71a9ef057eb9dde127e Mon Sep 17 00:00:00 2001 From: William Breathitt Gray Date: Thu, 20 Oct 2022 10:11:21 -0400 Subject: [PATCH] counter: 104-quad-8: Fix race getting function mode and direction The quad8_action_read() function checks the Count function mode and Count direction without first acquiring a lock. This is a race condition because the function mode could change by the time the direction is checked. Because the quad8_function_read() already acquires a lock internally, the quad8_function_read() is refactored to spin out the no-lock code to a new quad8_function_get() function. To resolve the race condition in quad8_action_read(), a lock is acquired before calling quad8_function_get() and quad8_direction_read() in order to get both function mode and direction atomically. Fixes: f1d8a071d45b ("counter: 104-quad-8: Add Generic Counter interface support") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20221020141121.15434-1-william.gray@linaro.org/ Signed-off-by: William Breathitt Gray diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index 77a863b7eefe..deed4afadb29 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -232,34 +232,45 @@ static const enum counter_function quad8_count_functions_list[] = { COUNTER_FUNCTION_QUADRATURE_X4, }; +static int quad8_function_get(const struct quad8 *const priv, const size_t id, + enum counter_function *const function) +{ + if (!priv->quadrature_mode[id]) { + *function = COUNTER_FUNCTION_PULSE_DIRECTION; + return 0; + } + + switch (priv->quadrature_scale[id]) { + case 0: + *function = COUNTER_FUNCTION_QUADRATURE_X1_A; + return 0; + case 1: + *function = COUNTER_FUNCTION_QUADRATURE_X2_A; + return 0; + case 2: + *function = COUNTER_FUNCTION_QUADRATURE_X4; + return 0; + default: + /* should never reach this path */ + return -EINVAL; + } +} + static int quad8_function_read(struct counter_device *counter, struct counter_count *count, enum counter_function *function) { struct quad8 *const priv = counter_priv(counter); - const int id = count->id; unsigned long irqflags; + int retval; spin_lock_irqsave(&priv->lock, irqflags); - if (priv->quadrature_mode[id]) - switch (priv->quadrature_scale[id]) { - case 0: - *function = COUNTER_FUNCTION_QUADRATURE_X1_A; - break; - case 1: - *function = COUNTER_FUNCTION_QUADRATURE_X2_A; - break; - case 2: - *function = COUNTER_FUNCTION_QUADRATURE_X4; - break; - } - else - *function = COUNTER_FUNCTION_PULSE_DIRECTION; + retval = quad8_function_get(priv, count->id, function); spin_unlock_irqrestore(&priv->lock, irqflags); - return 0; + return retval; } static int quad8_function_write(struct counter_device *counter, @@ -359,6 +370,7 @@ static int quad8_action_read(struct counter_device *counter, enum counter_synapse_action *action) { struct quad8 *const priv = counter_priv(counter); + unsigned long irqflags; int err; enum counter_function function; const size_t signal_a_id = count->synapses[0].signal->id; @@ -374,9 +386,21 @@ static int quad8_action_read(struct counter_device *counter, return 0; } - err = quad8_function_read(counter, count, &function); - if (err) + spin_lock_irqsave(&priv->lock, irqflags); + + /* Get Count function and direction atomically */ + err = quad8_function_get(priv, count->id, &function); + if (err) { + spin_unlock_irqrestore(&priv->lock, irqflags); + return err; + } + err = quad8_direction_read(counter, count, &direction); + if (err) { + spin_unlock_irqrestore(&priv->lock, irqflags); return err; + } + + spin_unlock_irqrestore(&priv->lock, irqflags); /* Default action mode */ *action = COUNTER_SYNAPSE_ACTION_NONE; @@ -389,10 +413,6 @@ static int quad8_action_read(struct counter_device *counter, return 0; case COUNTER_FUNCTION_QUADRATURE_X1_A: if (synapse->signal->id == signal_a_id) { - err = quad8_direction_read(counter, count, &direction); - if (err) - return err; - if (direction == COUNTER_COUNT_DIRECTION_FORWARD) *action = COUNTER_SYNAPSE_ACTION_RISING_EDGE; else