From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1883814-1518710824-2-3820434067087883228 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518710824; b=aJCz7TvUc3uLj8FKRIEIRDXq86eapqbEBMjadylgp7OsuU9 Hml2D2ekJ2UOUoCq9HljXlkZ5cik1NfsK2Fp9N47T908GsW4kJDczBWapu0jUibs KMqkBLwYJ/Rh4epWgwtEZ0InsbZcb0wioHxyEVPv9zcR/j4NRP8TdMJISJHNFPki R8/t3CIvMz7k71dvIXgXyK9MuXAGqm9/R3Ae6E5WyGkx3zgGJVvtZ5U7juq2YKVR 9JzjDLuEUcRp4qh0jRzBV/LjyHIysdZWFqr539wMrqUrhtsyY5GjPVIXL+lL4XC6 OZB13b3XSLJ5vZZmaAJ+G3wHkLu9LrmFIHmytuw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1518710824; bh=/QokFDUBF0m8Adq1pezowmdXC1 ZUQKwoplMOOvv1QiE=; b=DB9xoRg2z2V1xjR0UTH4pZz+eOOfT/j0ajPydEA4IJ XmW2xHxWih37fbsG36jP+6QrHFj8V2HimXaCgUGsZRQm8rLpa29jX0qDgMAXOYI5 M3SQG+vyHYT4u9RygtXc2qRELDaNxZmTUaKHvoPIHrZ8ebTWL7VWspCV9Rg5nivO 3Phdy7T8Y3lH4582VozKwOytscPyA+G1rnEf4oNIKhY+2mbOT6VDiOnidz+8pg3e auIGziTDQAqFeWIKz6gSRDlkxKdMWUNcCaeAzo7KTIMUKcBXhF3hnbUrjHGeAzbB PNNUEB1cqKBq1CLM4SOUhgAUGSK+vMYGWrZT35qPUXig== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1424557AbeBOPpy (ORCPT ); Thu, 15 Feb 2018 10:45:54 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:35140 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424535AbeBOPpw (ORCPT ); Thu, 15 Feb 2018 10:45:52 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Rasmus Villemoes , Tejun Heo , Arjan van de Ven , Adam Wallis , Lai Jiangshan , Andrew Morton , Linus Torvalds Subject: [PATCH 4.15 157/202] kernel/async.c: revert "async: simplify lowest_in_progress()" Date: Thu, 15 Feb 2018 16:17:37 +0100 Message-Id: <20180215151721.123971697@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151712.768794354@linuxfoundation.org> References: <20180215151712.768794354@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rasmus Villemoes commit 4f7e988e63e336827f4150de48163bed05d653bd upstream. This reverts commit 92266d6ef60c ("async: simplify lowest_in_progress()") which was simply wrong: In the case where domain is NULL, we now use the wrong offsetof() in the list_first_entry macro, so we don't actually fetch the ->cookie value, but rather the eight bytes located sizeof(struct list_head) further into the struct async_entry. On 64 bit, that's the data member, while on 32 bit, that's a u64 built from func and data in some order. I think the bug happens to be harmless in practice: It obviously only affects callers which pass a NULL domain, and AFAICT the only such caller is async_synchronize_full() -> async_synchronize_full_domain(NULL) -> async_synchronize_cookie_domain(ASYNC_COOKIE_MAX, NULL) and the ASYNC_COOKIE_MAX means that in practice we end up waiting for the async_global_pending list to be empty - but it would break if somebody happened to pass (void*)-1 as the data element to async_schedule, and of course also if somebody ever does a async_synchronize_cookie_domain(, NULL) with a "finite" cookie value. Maybe the "harmless in practice" means this isn't -stable material. But I'm not completely confident my quick git grep'ing is enough, and there might be affected code in one of the earlier kernels that has since been removed, so I'll leave the decision to the stable guys. Link: http://lkml.kernel.org/r/20171128104938.3921-1-linux@rasmusvillemoes.dk Fixes: 92266d6ef60c "async: simplify lowest_in_progress()" Signed-off-by: Rasmus Villemoes Acked-by: Tejun Heo Cc: Arjan van de Ven Cc: Adam Wallis Cc: Lai Jiangshan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/async.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) --- a/kernel/async.c +++ b/kernel/async.c @@ -84,20 +84,24 @@ static atomic_t entry_count; static async_cookie_t lowest_in_progress(struct async_domain *domain) { - struct list_head *pending; + struct async_entry *first = NULL; async_cookie_t ret = ASYNC_COOKIE_MAX; unsigned long flags; spin_lock_irqsave(&async_lock, flags); - if (domain) - pending = &domain->pending; - else - pending = &async_global_pending; + if (domain) { + if (!list_empty(&domain->pending)) + first = list_first_entry(&domain->pending, + struct async_entry, domain_list); + } else { + if (!list_empty(&async_global_pending)) + first = list_first_entry(&async_global_pending, + struct async_entry, global_list); + } - if (!list_empty(pending)) - ret = list_first_entry(pending, struct async_entry, - domain_list)->cookie; + if (first) + ret = first->cookie; spin_unlock_irqrestore(&async_lock, flags); return ret;