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=ham 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 2B4D2C47247 for ; Fri, 8 May 2020 12:54:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0CAE824958 for ; Fri, 8 May 2020 12:54:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588942472; bh=nfiwwpDz/de7q+n6W8S3wgYmXpKZ5Q6kBvbCxOI4mBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zOgAu50n/p1qXDsuoh+Lv4vp27w1+DcAnzf+ZLNGL2mczrNKwwyQ0VreICL5cOWVW LbU+vBghjMKeJjVC69kZmE2fl8IT6qApdNu90MK3LPAQC5+2TWABmfp0CHHnm5b/UI 6oKk4+IWl5b2ZMUuxNf03+KVEl0qmjmcKiZSD2NA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727969AbgEHMyb (ORCPT ); Fri, 8 May 2020 08:54:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:36750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730211AbgEHMy1 (ORCPT ); Fri, 8 May 2020 08:54:27 -0400 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 5CF822054F; Fri, 8 May 2020 12:54:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588942465; bh=nfiwwpDz/de7q+n6W8S3wgYmXpKZ5Q6kBvbCxOI4mBQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lA0GXtmhCX/5RDV581hrr9H0OWDfGRjMIGYgu4xu+sMJRw5ybBJZCX16nRi3ezN2k +rbjSCdDjMXH3zPLDqkK8NLFOMr0pD27ewNHF4y+VaT9YSpiqc7ouvBVu5fPKeN62J SbHs4MtwiMGUvs0ZxfQf+Beky4+JqF5KBWWonzSE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Heidi Fahim , Brendan Higgins , Heikki Krogerus , "Rafael J. Wysocki" Subject: [PATCH 5.4 33/50] Revert "software node: Simplify software_node_release() function" Date: Fri, 8 May 2020 14:35:39 +0200 Message-Id: <20200508123048.021195543@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508123043.085296641@linuxfoundation.org> References: <20200508123043.085296641@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Brendan Higgins commit 7589238a8cf37331607c3222a64ac3140b29532d upstream. This reverts commit 3df85a1ae51f6b256982fe9d17c2dc5bfb4cc402. The reverted commit says "It's possible to release the node ID immediately when fwnode_remove_software_node() is called, no need to wait for software_node_release() with that." However, releasing the node ID before waiting for software_node_release() to be called causes the node ID to be released before the kobject and the underlying sysfs entry; this means there is a period of time where a sysfs entry exists that is associated with an unallocated node ID. Once consequence of this is that there is a race condition where it is possible to call fwnode_create_software_node() with no parent node specified (NULL) and have it fail with -EEXIST because the node ID that was assigned is still associated with a stale sysfs entry that hasn't been cleaned up yet. Although it is difficult to reproduce this race condition under normal conditions, it can be deterministically reproduced with the following minconfig on UML: CONFIG_KUNIT_DRIVER_PE_TEST=y CONFIG_DEBUG_KERNEL=y CONFIG_DEBUG_OBJECTS=y CONFIG_DEBUG_OBJECTS_TIMERS=y CONFIG_DEBUG_KOBJECT_RELEASE=y CONFIG_KUNIT=y Running the tests with this configuration causes the following failure: kobject: 'node0' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 400) ok 1 - pe_test_uints sysfs: cannot create duplicate filename '/kernel/software_nodes/node0' CPU: 0 PID: 28 Comm: kunit_try_catch Not tainted 5.6.0-rc3-next-20200227 #14 kobject_add_internal failed for node0 with -EEXIST, don't try to register things with the same name in the same directory. kobject: 'node0' ((____ptrval____)): kobject_release, parent (____ptrval____) (delayed 100) # pe_test_uint_arrays: ASSERTION FAILED at drivers/base/test/property-entry-test.c:123 Expected node is not error, but is: -17 not ok 2 - pe_test_uint_arrays Reported-by: Heidi Fahim Signed-off-by: Brendan Higgins Reviewed-by: Heikki Krogerus Cc: 5.3+ # 5.3+ Signed-off-by: Rafael J. Wysocki Signed-off-by: Greg Kroah-Hartman --- drivers/base/swnode.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/drivers/base/swnode.c +++ b/drivers/base/swnode.c @@ -679,6 +679,13 @@ static void software_node_release(struct { struct swnode *swnode = kobj_to_swnode(kobj); + if (swnode->parent) { + ida_simple_remove(&swnode->parent->child_ids, swnode->id); + list_del(&swnode->entry); + } else { + ida_simple_remove(&swnode_root_ids, swnode->id); + } + if (swnode->allocated) { property_entries_free(swnode->node->properties); kfree(swnode->node); @@ -844,13 +851,6 @@ void fwnode_remove_software_node(struct if (!swnode) return; - if (swnode->parent) { - ida_simple_remove(&swnode->parent->child_ids, swnode->id); - list_del(&swnode->entry); - } else { - ida_simple_remove(&swnode_root_ids, swnode->id); - } - kobject_put(&swnode->kobj); } EXPORT_SYMBOL_GPL(fwnode_remove_software_node);