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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E590C41513 for ; Sat, 14 Oct 2023 23:01:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 83E358D0015; Sat, 14 Oct 2023 19:01:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7EEA48D0001; Sat, 14 Oct 2023 19:01:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6DC388D0015; Sat, 14 Oct 2023 19:01:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 633B58D0001 for ; Sat, 14 Oct 2023 19:01:14 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 3B1781A071F for ; Sat, 14 Oct 2023 23:01:14 +0000 (UTC) X-FDA: 81345589668.20.A6FC65C Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf28.hostedemail.com (Postfix) with ESMTP id 7E5ECC001D for ; Sat, 14 Oct 2023 23:01:12 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LY68QcCW; spf=pass (imf28.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1697324472; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=3k1tDiKTe9JqL91uCpIl/7+8yI/SrAoJEHJPUxlKYC8=; b=BlRbpIKLXtzNY5J510pAIgcy2DyKQ3tVXudqU8j8qJJYPmtWTlt2iODgVT8VVCh7y42eAd a8Ns+1tFs/UnOygKJCNg4mS1CtgpzSwM9T2ikAEUZyg4Gqd9kEir+KIZtKKlm7ZoE1rRTC TEv57FCL/5j6GMW4hSC7fYyAMWoh55I= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LY68QcCW; spf=pass (imf28.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1697324472; a=rsa-sha256; cv=none; b=ysDlkY/SLIl16xwAxHT5qbmn5FYYb0hoC6vBJ0jlbypvLrXZ6c/1JwyMgWyJ6dQ6svyQz7 hoUGrDW/OcciR9LAlWXFfAugCFZ/643XITUW0LwFSXANd5cC8+y2S5yQvG8Fg0+WHPMK4W QgQV0uQa/Hl/Wu6tTcV5W2pu9UkCMkU= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 6FC7D602FB; Sat, 14 Oct 2023 23:01:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F3779C433C7; Sat, 14 Oct 2023 23:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1697324471; bh=XO7DKNf9VXgcblgzYunjPQ6Iz024GpQIbrDxjVO0LAM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LY68QcCWmdmIub7wuID3ZVKrVdvvduGFlwlEMqEpoBVYlofT2TL49Zl7GDwKGg9wC 4nACqo9c+RFqVnJE0dzTgb1OseNF2rfdAsRyCBdHT1dBVkaraUp87+kKxLjjL0RVRk ZmV+p5htCLF9BNmVULCfMQ9LevNNDEGa8eB9rik8= Date: Sat, 14 Oct 2023 16:01:04 -0700 From: Andrew Morton To: Huai-Yuan Liu <810974084@qq.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/page_alloc.c: function call alloc_percpu() unchecked Message-Id: <20231014160104.19912de669475deec235702d@linux-foundation.org> In-Reply-To: <20231012082535.7135-1-810974084@qq.com> References: <20231012082535.7135-1-810974084@qq.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 7E5ECC001D X-Rspam-User: X-Stat-Signature: 9nemf6rzd8hw5fs8cspsxs4fnp38myd3 X-Rspamd-Server: rspam01 X-HE-Tag: 1697324472-503031 X-HE-Meta: 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 wJ/ar5X8 q/2TVnrYHYdIBQXGxrz6UoTlSd/OWunAKDMnFooGJZxfU3QM8bNtEImWfS0y0O1GWieYciwdZYJ5yAUbP84AAuAivoqyi/PdNjC1vEZbYxuW86j8bvg4b2Cobl+lW7DYocfb41+CKqH0+OyeSx2AgrQySwB53yZo9/Ug9O6DTI3yZ30Wu62EsBhfvcSchEyl21ylsg6meMKQ7kxk1n4OYESCOYkdQjgMOw1ajgBwmRD0hyeiOkHZCmikXKwcDrYR0Q1VnoH0IfPt5ixK6rnhrZbi3XAG6xM5VZV9Xg8NIBynLlx0= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 12 Oct 2023 01:25:35 -0700 Huai-Yuan Liu <810974084@qq.com> wrote: > The function call alloc_percpu() returns a pointer to the memory address, > but it hasn't been checked. Our static analysis tool indicates that null > pointer dereference may exist in pointer zone->per_cpu_pageset. It is > always safe to judge the null pointer before use. > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5390,6 +5390,8 @@ void __meminit setup_zone_pageset(struct zone *zone) > zone->per_cpu_zonestats = alloc_percpu(struct per_cpu_zonestat); > > zone->per_cpu_pageset = alloc_percpu(struct per_cpu_pages); > + if (!zone->per_cpu_pageset) > + return; > for_each_possible_cpu(cpu) { > struct per_cpu_pages *pcp; > struct per_cpu_zonestat *pzstats; I suppose as it's __meminit, yes, we should be checking here. In which case we should also be checking the alloc_percpu() two lines earlier and we should be freeing zone->per_cpu_zonestats if this second alloc_percpu() fails. And we should be propagating the overall failure back to higher layers whihc then handle it so the kernel won't immediately crash anwyay.