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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 50072C11F64 for ; Tue, 29 Jun 2021 02:35:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39EBB61A2B for ; Tue, 29 Jun 2021 02:35:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231717AbhF2Ch3 (ORCPT ); Mon, 28 Jun 2021 22:37:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:58162 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231805AbhF2Ch2 (ORCPT ); Mon, 28 Jun 2021 22:37:28 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 25C2461D02; Tue, 29 Jun 2021 02:35:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1624934102; bh=4cE/8HJP5sT8ERsgvJylaiUPxIW4s+gi1dcR86jyYok=; h=Date:From:To:Subject:In-Reply-To:From; b=jC4PtGh4iaJp2vfXE1CmmK5zR96MsIEFOKbjzc44b1bgpFVhc8EPObC71BC7o2MSD LcRinc3dvasFLORgF2+uCUHS5i2Cjxlb5s3mfdZAenqSvOYhkjMwT2KqrzaYtHD3aH IE4NzIdF5zgqltA0skz9BCMtiKKAo1I2LTsxunAU= Date: Mon, 28 Jun 2021 19:35:01 -0700 From: Andrew Morton To: akpm@linux-foundation.org, catalin.marinas@arm.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, yanfei.xu@windriver.com Subject: [patch 033/192] mm/kmemleak: fix possible wrong memory scanning period Message-ID: <20210629023501.ZQbWNxCiI%akpm@linux-foundation.org> In-Reply-To: <20210628193256.008961950a714730751c1423@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yanfei Xu Subject: mm/kmemleak: fix possible wrong memory scanning period This commit contains 3 modifications: 1. Convert the type of jiffies_scan_wait to "unsigned long". 2. Use READ/WRITE_ONCE() for accessing "jiffies_scan_wait". 3. Fix the possible wrong memory scanning period. If you set a large memory scanning period like blow, then the "secs" variable will be non-zero, however the value of "jiffies_scan_wait" will be zero. echo "scan=0x10000000" > /sys/kernel/debug/kmemleak It is because the type of the msecs_to_jiffies()'s parameter is "unsigned int", and the "secs * 1000" is larger than its max value. This in turn leads a unexpected jiffies_scan_wait, maybe zero. We corret it by replacing kstrtoul() with kstrtouint(), and check the msecs to prevent it larger than UINT_MAX. Link: https://lkml.kernel.org/r/20210613174022.23044-1-yanfei.xu@windriver.com Signed-off-by: Yanfei Xu Acked-by: Catalin Marinas Signed-off-by: Andrew Morton --- mm/kmemleak.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- a/mm/kmemleak.c~mm-kmemleak-fix-the-possible-wrong-memory-scanning-period +++ a/mm/kmemleak.c @@ -219,7 +219,7 @@ static struct task_struct *scan_thread; static unsigned long jiffies_min_age; static unsigned long jiffies_last_scan; /* delay between automatic memory scannings */ -static signed long jiffies_scan_wait; +static unsigned long jiffies_scan_wait; /* enables or disables the task stacks scanning */ static int kmemleak_stack_scan = 1; /* protects the memory scanning, parameters and debug/kmemleak file access */ @@ -1567,7 +1567,7 @@ static int kmemleak_scan_thread(void *ar } while (!kthread_should_stop()) { - signed long timeout = jiffies_scan_wait; + signed long timeout = READ_ONCE(jiffies_scan_wait); mutex_lock(&scan_mutex); kmemleak_scan(); @@ -1807,14 +1807,20 @@ static ssize_t kmemleak_write(struct fil else if (strncmp(buf, "scan=off", 8) == 0) stop_scan_thread(); else if (strncmp(buf, "scan=", 5) == 0) { - unsigned long secs; + unsigned secs; + unsigned long msecs; - ret = kstrtoul(buf + 5, 0, &secs); + ret = kstrtouint(buf + 5, 0, &secs); if (ret < 0) goto out; + + msecs = secs * MSEC_PER_SEC; + if (msecs > UINT_MAX) + msecs = UINT_MAX; + stop_scan_thread(); - if (secs) { - jiffies_scan_wait = msecs_to_jiffies(secs * 1000); + if (msecs) { + WRITE_ONCE(jiffies_scan_wait, msecs_to_jiffies(msecs)); start_scan_thread(); } } else if (strncmp(buf, "scan", 4) == 0) _