From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-476314-1519833686-2-5093032540041818064 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 0.249, 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='CN', FromHeader='uk', 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=1519833685; b=M0UcDy9vHBswOLVfYxElFHeIHrr1XUVIgq1b0oSibF1fEkE FJ+YSix/Ha4/WJViez8SXOBmzj+lz9tn7cWW2TnSK+YKMDBx3OC/LIF2A4LihP/4 mG8mNnJd2pw6r/5pMTglMMPCy6pTwoQvCxJFmS1cdUvr08DhIlpMLw6k48gyE/Eg 3YL4d1TjB+8egzxqXM9Y4VELcJn2n1usDjsmThf+STBF1OQsj1VO3oQjmg1vJBOB JEe5csiC0D0neBexCv1psPIcYppTxObTsEAPz8o2lslXKKf/eIFcfsKJ6q7uj7eq CAZuwDMBXpo4GkkyFtZXtXu0bz2l8qo2MqHYFgw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=content-type:content-transfer-encoding :mime-version:from:to:cc:date:message-id:subject:in-reply-to :sender:list-id; s=arctest; t=1519833685; bh=o/xQcggaxGMUuTQhS+/ yA3blO93FIQgFJz5N2wtTLQc=; b=Sw4L8ozNQTCnjR03K9bMmbL4kYjSybnS46q JRKRLlR0Rw13ip2wc64habYmc/C/EdZlOWmqLU23BMw/T8iRG7N6xuF+Wme9g61K wzI7k8qmXAeLu0wcPm8z9oIyRKjBhQJt9KmQ3V//K8N/Ni7umdR9sPFdRRCl4FN4 q2le7fMEmQXUxlcIHkhVYOxtTf+owOgf/J6UAB1AQ/SaChTMoTQoayx+OZathBF+ A6PVJPm02fxCdjosGEvKxV+PpvM1+mJXEgWYesTluSNBxuSs5bOqxYAseBwqD7hf P9NQzESKgafunbRkW+tY+b8fIlAIXRO7EQGmVNv3mYIMzChF/ZA== ARC-Authentication-Results: i=1; mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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=decadent.org.uk header.result=pass header_is_org_domain=yes Authentication-Results: mx2.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=decadent.org.uk; 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=decadent.org.uk header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932100AbeB1QBI (ORCPT ); Wed, 28 Feb 2018 11:01:08 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34688 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932120AbeB1QBG (ORCPT ); Wed, 28 Feb 2018 11:01:06 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Oleg Nesterov" , "TSUKADA Koutaro" , "Al Viro" , "Linus Torvalds" Date: Wed, 28 Feb 2018 15:20:18 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 169/254] kernel/acct.c: fix the acct->needcheck check in check_free_space() In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false 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: 3.16.55-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Oleg Nesterov commit 4d9570158b6260f449e317a5f9ed030c2504a615 upstream. As Tsukada explains, the time_is_before_jiffies(acct->needcheck) check is very wrong, we need time_is_after_jiffies() to make sys_acct() work. Ignoring the overflows, the code should "goto out" if needcheck > jiffies, while currently it checks "needcheck < jiffies" and thus in the likely case check_free_space() does nothing until jiffies overflow. In particular this means that sys_acct() is simply broken, acct_on() sets acct->needcheck = jiffies and expects that check_free_space() should set acct->active = 1 after the free-space check, but this won't happen if jiffies increments in between. This was broken by commit 32dc73086015 ("get rid of timer in kern/acct.c") in 2011, then another (correct) commit 795a2f22a8ea ("acct() should honour the limits from the very beginning") made the problem more visible. Link: http://lkml.kernel.org/r/20171213133940.GA6554@redhat.com Fixes: 32dc73086015 ("get rid of timer in kern/acct.c") Reported-by: TSUKADA Koutaro Suggested-by: TSUKADA Koutaro Signed-off-by: Oleg Nesterov Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- kernel/acct.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/acct.c +++ b/kernel/acct.c @@ -107,7 +107,7 @@ static int check_free_space(struct bsd_a spin_lock(&acct_lock); res = acct->active; - if (!file || time_is_before_jiffies(acct->needcheck)) + if (!file || time_is_after_jiffies(acct->needcheck)) goto out; spin_unlock(&acct_lock);