From patchwork Tue Sep 29 10:56:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 263057 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=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 14CCCC4727F for ; Tue, 29 Sep 2020 12:15:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C240C20759 for ; Tue, 29 Sep 2020 12:15:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601381707; bh=kNFZsopbVyVAJ8OKMfB9Qlukt+X2Zi5I8g5+zko9C/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2vOxLcPIfd4e076Gduj32ReKWljzyH10N805M8NdgFHrN4zdADj7Sua+9r4zwERQU aiGNWAIywAVeQkjHdu/SQx/0L23Lv7FV95xVrngQeKBeof2tXmGigmD5Km/I29tXjD My17oiIFcmbiFkv/Yke5DSgEs+D77Pmb3ulTjnfk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730489AbgI2MPG (ORCPT ); Tue, 29 Sep 2020 08:15:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:58078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728388AbgI2Lh2 (ORCPT ); Tue, 29 Sep 2020 07:37:28 -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 A0D3523B21; Tue, 29 Sep 2020 11:33:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601379226; bh=kNFZsopbVyVAJ8OKMfB9Qlukt+X2Zi5I8g5+zko9C/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y+XR4WAilYBvma41mD61p+qAc5yn3qPoMoOcUC29Yc790Pf8YAsWFbYhjkABh68DT TSpK1RGwAD1v2HXRkXH5R+BOMYRtVKVOF3q1AreJGrjlnpJ1owE/5dcLcFocyzL7Qf M2ZNVE0KvU6A6J8DJ20RAOUNqCDdySnnDftwqzhM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xiaoming Ni , Vasily Averin , Andrew Morton , Alexey Dobriyan , Anna Schumaker , Arjan van de Ven , "J. Bruce Fields" , Chuck Lever , "David S. Miller" , Jeff Layton , Andy Lutomirski , Ingo Molnar , Nadia Derbey , "Paul E. McKenney" , Sam Protsenko , Alan Stern , Thomas Gleixner , Trond Myklebust , Viresh Kumar , YueHaibing , Linus Torvalds , Sasha Levin Subject: [PATCH 5.4 069/388] kernel/notifier.c: intercept duplicate registrations to avoid infinite loops Date: Tue, 29 Sep 2020 12:56:40 +0200 Message-Id: <20200929110013.833689836@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200929110010.467764689@linuxfoundation.org> References: <20200929110010.467764689@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xiaoming Ni [ Upstream commit 1a50cb80f219c44adb6265f5071b81fc3c1deced ] Registering the same notifier to a hook repeatedly can cause the hook list to form a ring or lose other members of the list. case1: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); case2: An infinite loop in notifier_chain_register() can cause soft lockup atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_call_chain(&test_notifier_list, 0, NULL); case3: lose other hook test2 atomic_notifier_chain_register(&test_notifier_list, &test1); atomic_notifier_chain_register(&test_notifier_list, &test2); atomic_notifier_chain_register(&test_notifier_list, &test1); case4: Unregister returns 0, but the hook is still in the linked list, and it is not really registered. If you call notifier_call_chain after ko is unloaded, it will trigger oops. If the system is configured with softlockup_panic and the same hook is repeatedly registered on the panic_notifier_list, it will cause a loop panic. Add a check in notifier_chain_register(), intercepting duplicate registrations to avoid infinite loops Link: http://lkml.kernel.org/r/1568861888-34045-2-git-send-email-nixiaoming@huawei.com Signed-off-by: Xiaoming Ni Reviewed-by: Vasily Averin Reviewed-by: Andrew Morton Cc: Alexey Dobriyan Cc: Anna Schumaker Cc: Arjan van de Ven Cc: J. Bruce Fields Cc: Chuck Lever Cc: David S. Miller Cc: Jeff Layton Cc: Andy Lutomirski Cc: Ingo Molnar Cc: Nadia Derbey Cc: "Paul E. McKenney" Cc: Sam Protsenko Cc: Alan Stern Cc: Thomas Gleixner Cc: Trond Myklebust Cc: Viresh Kumar Cc: Xiaoming Ni Cc: YueHaibing Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- kernel/notifier.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/notifier.c b/kernel/notifier.c index 157d7c29f7207..f6d5ffe4e72ec 100644 --- a/kernel/notifier.c +++ b/kernel/notifier.c @@ -23,7 +23,10 @@ static int notifier_chain_register(struct notifier_block **nl, struct notifier_block *n) { while ((*nl) != NULL) { - WARN_ONCE(((*nl) == n), "double register detected"); + if (unlikely((*nl) == n)) { + WARN(1, "double register detected"); + return 0; + } if (n->priority > (*nl)->priority) break; nl = &((*nl)->next);