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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 41772C43464 for ; Fri, 18 Sep 2020 03:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E547F2083B for ; Fri, 18 Sep 2020 03:11:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600398662; bh=kNFZsopbVyVAJ8OKMfB9Qlukt+X2Zi5I8g5+zko9C/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rwXhtsthDy/WEixGOTm7jrNPZ2O+nsrggGYMHcSFKG2W8bbIslINz3UYj8lfsYtwh xgiYi3G2pxtFiLSQG9j/wBVOBbpn5zS4TNlVpYT0mWOSgIwsaed86p/wvoxapOUur3 zSSp610vqtDCGWvkgVBvHT86ZcPnF3847KAqm1Y4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728245AbgIRDLB (ORCPT ); Thu, 17 Sep 2020 23:11:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:47970 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726822AbgIRCCj (ORCPT ); Thu, 17 Sep 2020 22:02:39 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4A19A208DB; Fri, 18 Sep 2020 02:02:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600394558; bh=kNFZsopbVyVAJ8OKMfB9Qlukt+X2Zi5I8g5+zko9C/A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cXJG1FJf52NWQKRws/DivkesxnzcwRmdJXvR5LObG1xih9DnIRF9F+Tmkbm5bWagc YJTs7OW8fOCHTmUJ8zIyUbLoWfK5+YrxAYlwbU/bUgU3oYhnhBkhwP3nZG4l2KNofn t96fhYLDWQSiX4OvZmVqIrmxQhLEtEGrHcoXzCDY= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: 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 AUTOSEL 5.4 072/330] kernel/notifier.c: intercept duplicate registrations to avoid infinite loops Date: Thu, 17 Sep 2020 21:56:52 -0400 Message-Id: <20200918020110.2063155-72-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org> References: <20200918020110.2063155-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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); -- 2.25.1