From patchwork Fri Dec 9 10:55:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jinjie Ruan X-Patchwork-Id: 31723 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:f944:0:0:0:0:0 with SMTP id q4csp707188wrr; Fri, 9 Dec 2022 03:08:17 -0800 (PST) X-Google-Smtp-Source: AA0mqf56f5A3GK20GE/c1F410/I+p5GLRJD6XQrH6hUe50Q0bObU73+LZ37gMMiBkkcbbz/pMSZG X-Received: by 2002:a05:6402:378c:b0:461:cdda:4004 with SMTP id et12-20020a056402378c00b00461cdda4004mr4529569edb.10.1670584096811; Fri, 09 Dec 2022 03:08:16 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1670584096; cv=none; d=google.com; s=arc-20160816; b=vzyfoKnloxT5htYTHV7LjhpSg0bXmCixGFK8xLAUJbIF8GQuIhz5WhdjLz8PXRyPHx M40D3MHolfIF3nH6kbCtK0T4kcro8sNqhD4ytBKzxbBeVIbMJtVOH76bl2iBpJsJEVsr 4nB9PPaUbHVyiNMvtER+x+ha7iuw+RvzgQkLrZ0lPjicQix3b1KPCMVOYvpEg4HEHjeU cPOKvVb+CM8WD/ScYvFnodvDp5CqpUkNAy1fakipjdGkg1ZxctpJ2chX1JGCcmJoWHlX eZtiagsnWle2Y9Y91RqM37vYYUbe3uGmG88DaZJ/6PULvVNTAbHYO4ndozPG/3JLKj/U MQog== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from; bh=wDgujAAvbSEdZyx15/AW2X0MN55UlC5WseXvD2Ku71U=; b=d+zR5a07w3kMu58Q4gh3UJreZnzHgKHGk+R2DGyS1mtAOUeoaV/MWP7ZQdZ2Pn1u2H dFrPRljLXJO3qPzYeAeQq7QnOgb3Q9E9E6eyG82qD0tZ2nKNElJE1dh8aWtqRiJe7Axq +087AFuoy1jh3S97WJ0ha2rZwOUjSe2wy8He1STmgneuJ59lIjvUgU0EGqSEa1aSyizo IkQ3Fjug4qM46Oe5oNFjnPQkpMRauPXT/f+kx2QNPJoqdQGB9i2UmedIWqvTV0u7KvvE RTcdXJUrg4zTjjp0c3LnjDR03wqENO/RYZ+PC0XANsZFr6jdCXpyXRopHrexmTvDw9wf hleA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id r12-20020aa7d14c000000b00469c5cc855csi1021007edo.518.2022.12.09.03.07.52; Fri, 09 Dec 2022 03:08:16 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=huawei.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229821AbiLIK7a (ORCPT + 99 others); Fri, 9 Dec 2022 05:59:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229696AbiLIK7Y (ORCPT ); Fri, 9 Dec 2022 05:59:24 -0500 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E611D5447B for ; Fri, 9 Dec 2022 02:59:22 -0800 (PST) Received: from kwepemi500008.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4NT7Kz0RGQzJqMN; Fri, 9 Dec 2022 18:58:31 +0800 (CST) Received: from huawei.com (10.67.175.83) by kwepemi500008.china.huawei.com (7.221.188.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 9 Dec 2022 18:59:20 +0800 From: ruanjinjie To: , , , , , CC: Subject: [PATCH] arm64: fix a concurrency issue in emulation_proc_handler() Date: Fri, 9 Dec 2022 18:55:56 +0800 Message-ID: <20221209105556.47621-1-ruanjinjie@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.67.175.83] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500008.china.huawei.com (7.221.188.139) X-CFilter-Loop: Reflected X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1751734390285293374?= X-GMAIL-MSGID: =?utf-8?q?1751734390285293374?= In emulation_proc_handler(), read and write operations are performed on insn->current_mode. In the concurrency scenario, mutex only protects writing insn->current_mode, and not protects the read. Suppose there are two concurrent tasks, task1 updates insn->current_mode to INSN_EMULATE in the critical section, the prev_mode of task2 is still the old data INSN_UNDEF of insn->current_mode. As a result, two tasks call update_insn_emulation_mode twice with prev_mode = INSN_UNDEF and current_mode = INSN_EMULATE, then call register_emulation_hooks twice, resulting in a list_add double problem. Call trace: __list_add_valid+0xd8/0xe4 register_undef_hook+0x94/0x13c update_insn_emulation_mode+0xd0/0x12c emulation_proc_handler+0xd8/0xf4 proc_sys_call_handler+0x140/0x250 proc_sys_write+0x1c/0x2c new_sync_write+0xec/0x18c vfs_write+0x214/0x2ac ksys_write+0x70/0xfc __arm64_sys_write+0x24/0x30 el0_svc_common.constprop.0+0x7c/0x1bc do_el0_svc+0x2c/0x94 el0_svc+0x20/0x30 el0_sync_handler+0xb0/0xb4 el0_sync+0x160/0x180 Fixes: af483947d472 ("arm64: fix oops in concurrently setting insn_emulation sysctls") Signed-off-by: ruanjinjie Acked-by: Mark Rutland --- arch/arm64/kernel/armv8_deprecated.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index fb0e7c7b2e20..d33e5d9e6990 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -208,10 +208,12 @@ static int emulation_proc_handler(struct ctl_table *table, int write, loff_t *ppos) { int ret = 0; - struct insn_emulation *insn = container_of(table->data, struct insn_emulation, current_mode); - enum insn_emulation_mode prev_mode = insn->current_mode; + struct insn_emulation *insn; + enum insn_emulation_mode prev_mode; mutex_lock(&insn_emulation_mutex); + insn = container_of(table->data, struct insn_emulation, current_mode); + prev_mode = insn->current_mode; ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); if (ret || !write || prev_mode == insn->current_mode)