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 X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D9EBC4727C for ; Tue, 29 Sep 2020 12:44:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDD6C20725 for ; Tue, 29 Sep 2020 12:44:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601383488; bh=rzBnvB+cNBmYeoMD+Rr2ep0RoO4PwGY5lqpNy7/AXFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=N5laTYPx6k8GAfDX2BFgo08oyf/a+YX0F39F5TX1EzmYfXCFPuRlIm0W53T3ETtSK 55tzXyVVh67K2GjrjtLsUkmFHgGOb1tnlGNP64xzXm7HTIgroeGQva1ItLY+DHCPMv dhO6wfhka8gCzoG9nAFhWsdsinqbdAFCeLbA1/jg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387511AbgI2Mor (ORCPT ); Tue, 29 Sep 2020 08:44:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:47402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728701AbgI2LIZ (ORCPT ); Tue, 29 Sep 2020 07:08:25 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 89DDE22204; Tue, 29 Sep 2020 11:08:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601377684; bh=rzBnvB+cNBmYeoMD+Rr2ep0RoO4PwGY5lqpNy7/AXFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gFuTmqKqZzs5YzMVwOtgdqqLeHtL2lwcK6IsHI++VS95aj1VtrKoNsTsu7DQ4PPbN DHOXaGearkTf1sxWvRl05l5Cy8Qn5SwwmtLU9geBOvujDWbn0/hhOS330GvCfKjQQZ T908vHVWCY7Ve/df3l2Ip9Mz/pOuyCxPF49DBzNg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.9 035/121] ACPI: EC: Reference count query handlers under lock Date: Tue, 29 Sep 2020 12:59:39 +0200 Message-Id: <20200929105931.923844317@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929105930.172747117@linuxfoundation.org> References: <20200929105930.172747117@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rafael J. Wysocki [ Upstream commit 3df663a147fe077a6ee8444ec626738946e65547 ] There is a race condition in acpi_ec_get_query_handler() theoretically allowing query handlers to go away before refernce counting them. In order to avoid it, call kref_get() on query handlers under ec->mutex. Also simplify the code a bit while at it. Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- drivers/acpi/ec.c | 16 ++++------------ 1 file changed, 4 insertions(+), 12 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 307b3e28f34ce..8781b5dc97f1c 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -1049,29 +1049,21 @@ void acpi_ec_unblock_transactions(void) /* -------------------------------------------------------------------------- Event Management -------------------------------------------------------------------------- */ -static struct acpi_ec_query_handler * -acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler) -{ - if (handler) - kref_get(&handler->kref); - return handler; -} - static struct acpi_ec_query_handler * acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value) { struct acpi_ec_query_handler *handler; - bool found = false; mutex_lock(&ec->mutex); list_for_each_entry(handler, &ec->list, node) { if (value == handler->query_bit) { - found = true; - break; + kref_get(&handler->kref); + mutex_unlock(&ec->mutex); + return handler; } } mutex_unlock(&ec->mutex); - return found ? acpi_ec_get_query_handler(handler) : NULL; + return NULL; } static void acpi_ec_query_handler_release(struct kref *kref) -- 2.25.1