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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 BF2B2C2D0D1 for ; Thu, 19 Dec 2019 19:04:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 941A3222C2 for ; Thu, 19 Dec 2019 19:04:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576782270; bh=wIOxz9h/1fpnplrRfLmE8p8swLUE7URyYaiVcoUWFug=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=v1YhVBbxPN5VQKO0UMEduiOg+EwH/YiS6XQnIawN3sDACNy/lxixs5Fwoz7gG95o4 DJ4gUpbNW0FsEY3uHaixtWqCyVWqJSU9LBZ8nQ0c9ZzPRxfP3JXEutplO9vz1W4mQN eqdkH9jDUBRlmGG0Nsxh9+HU6aEWuZbC45NZit3k= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729419AbfLSSrH (ORCPT ); Thu, 19 Dec 2019 13:47:07 -0500 Received: from mail.kernel.org ([198.145.29.99]:39996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727462AbfLSSrH (ORCPT ); Thu, 19 Dec 2019 13:47:07 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 9D4C024672; Thu, 19 Dec 2019 18:47:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576781226; bh=wIOxz9h/1fpnplrRfLmE8p8swLUE7URyYaiVcoUWFug=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uI2ZbCX+U6XsXVDktR8AR/w/aABLYlDg2T9lSP27g+hbKqj0zOXMqdhun59YICzbt PM6JBR/SwDKaaCJ5i1BP0HACyWDiyTdvlTVda1mpHvJcnOLZQvvMJgcJ5/EHmrs+JK n4x2kh07TiUKJcVhoI8d1imxQysm83VfzaJcEOyA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Francesco Ruggeri , Dmitry Safonov <0x7f454c46@gmail.com>, "Rafael J. Wysocki" Subject: [PATCH 4.9 135/199] ACPI: OSL: only free map once in osl.c Date: Thu, 19 Dec 2019 19:33:37 +0100 Message-Id: <20191219183222.569036787@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191219183214.629503389@linuxfoundation.org> References: <20191219183214.629503389@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Francesco Ruggeri commit 833a426cc471b6088011b3d67f1dc4e147614647 upstream. acpi_os_map_cleanup checks map->refcount outside of acpi_ioremap_lock before freeing the map. This creates a race condition the can result in the map being freed more than once. A panic can be caused by running for ((i=0; i<10; i++)) do for ((j=0; j<100000; j++)) do cat /sys/firmware/acpi/tables/data/BERT >/dev/null done & done This patch makes sure that only the process that drops the reference to 0 does the freeing. Fixes: b7c1fadd6c2e ("ACPI: Do not use krefs under a mutex in osl.c") Signed-off-by: Francesco Ruggeri Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com> Cc: All applicable Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/acpi/osl.c | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) --- a/drivers/acpi/osl.c +++ b/drivers/acpi/osl.c @@ -375,19 +375,21 @@ void *__ref acpi_os_map_memory(acpi_phys } EXPORT_SYMBOL_GPL(acpi_os_map_memory); -static void acpi_os_drop_map_ref(struct acpi_ioremap *map) +/* Must be called with mutex_lock(&acpi_ioremap_lock) */ +static unsigned long acpi_os_drop_map_ref(struct acpi_ioremap *map) { - if (!--map->refcount) + unsigned long refcount = --map->refcount; + + if (!refcount) list_del_rcu(&map->list); + return refcount; } static void acpi_os_map_cleanup(struct acpi_ioremap *map) { - if (!map->refcount) { - synchronize_rcu_expedited(); - acpi_unmap(map->phys, map->virt); - kfree(map); - } + synchronize_rcu_expedited(); + acpi_unmap(map->phys, map->virt); + kfree(map); } /** @@ -407,6 +409,7 @@ static void acpi_os_map_cleanup(struct a void __ref acpi_os_unmap_iomem(void __iomem *virt, acpi_size size) { struct acpi_ioremap *map; + unsigned long refcount; if (!acpi_gbl_permanent_mmap) { __acpi_unmap_table(virt, size); @@ -420,10 +423,11 @@ void __ref acpi_os_unmap_iomem(void __io WARN(true, PREFIX "%s: bad address %p\n", __func__, virt); return; } - acpi_os_drop_map_ref(map); + refcount = acpi_os_drop_map_ref(map); mutex_unlock(&acpi_ioremap_lock); - acpi_os_map_cleanup(map); + if (!refcount) + acpi_os_map_cleanup(map); } EXPORT_SYMBOL_GPL(acpi_os_unmap_iomem); @@ -464,6 +468,7 @@ void acpi_os_unmap_generic_address(struc { u64 addr; struct acpi_ioremap *map; + unsigned long refcount; if (gas->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) return; @@ -479,10 +484,11 @@ void acpi_os_unmap_generic_address(struc mutex_unlock(&acpi_ioremap_lock); return; } - acpi_os_drop_map_ref(map); + refcount = acpi_os_drop_map_ref(map); mutex_unlock(&acpi_ioremap_lock); - acpi_os_map_cleanup(map); + if (!refcount) + acpi_os_map_cleanup(map); } EXPORT_SYMBOL(acpi_os_unmap_generic_address);