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 BDE7EC4345F for ; Mon, 29 Apr 2024 16:23:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 543AB6B009C; Mon, 29 Apr 2024 12:23:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4F4146B009D; Mon, 29 Apr 2024 12:23:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3BBC26B009E; Mon, 29 Apr 2024 12:23:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 1D4336B009C for ; Mon, 29 Apr 2024 12:23:18 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 91DAF80645 for ; Mon, 29 Apr 2024 16:23:17 +0000 (UTC) X-FDA: 82063089234.13.BD0F627 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf29.hostedemail.com (Postfix) with ESMTP id 70ACD120020 for ; Mon, 29 Apr 2024 16:23:15 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LrKzQntE; spf=pass (imf29.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 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=1714407796; 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=ECKsR7gSc7PqtSVqfVdKo6YqBA37ol9wKk+epOGXAQY=; b=xehVQtkcSUcaPJtLssXa5VT7ZMz26rhY7VwnUw4OTZhgXfiyJOrSn+VbLYLgevpxbg2wab 05FyflFOtwNhYgrYnlbBBHOvV11kt5ujg2ajyGXTD3SmWIxUT2qouAERNT+5T8ODfs6p6j k0v5BjNNsszZ1cQ7SQAcjwJ2XJiiylw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1714407796; a=rsa-sha256; cv=none; b=7nV4MaDeKaP9DFeTK9nJahEPbnca9QGc5pp1PhSJJ6y1uws9bp5tpLJViRwFGfb0TzPZ2N hOX2WM6KwfCwuROqCt2ghESH3CIZ2l8nKdV+TQwLhUYpleUvnoRAGn0wYAVsx4XcezPGPP N1LozEcZ98jPQr5NoAhBZobwKzRRNaE= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LrKzQntE; spf=pass (imf29.hostedemail.com: domain of akpm@linux-foundation.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id B84E0CE0CF0; Mon, 29 Apr 2024 16:23:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90B2FC113CD; Mon, 29 Apr 2024 16:23:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1714407789; bh=leIF1FkkaAIGefMANabaMQGP376d/EtqqslqBj0skp4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LrKzQntEeZj2BfgfUv6nBmFwPfgwHh0sru4q3QdBSe8rnwxUpw/sH2YaoWBJqsi1G 46aNixPeM47BJAbqbRQPFcSOBRXjr3JJObNiK1TSFoRp9nlnMo50clkx0wOXSS65F8 uJyH9w7LEd7Y8cA/y9koOTgq/+WCXzpbUnWO+FtE= Date: Mon, 29 Apr 2024 09:23:07 -0700 From: Andrew Morton To: Luis Chamberlain Cc: ziy@nvidia.com, linux-mm@kvack.org, fstests@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, willy@infradead.org, hare@suse.de, john.g.garry@oracle.com, p.raghav@samsung.com, da.gomez@samsung.com Subject: Re: [PATCH 1/2] mm/huge_memory: skip invalid debugfs file entry for folio split Message-Id: <20240429092307.37bf51c79f70bad4922f6277@linux-foundation.org> In-Reply-To: References: <20240424225449.1498244-1-mcgrof@kernel.org> <20240424225449.1498244-2-mcgrof@kernel.org> <20240425140126.2a62a5ec686813ee7deea658@linux-foundation.org> 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-Rspam-User: X-Stat-Signature: go7pf9ytz1e48c4eskzqmd6acp5hn9d9 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 70ACD120020 X-HE-Tag: 1714407795-658684 X-HE-Meta: U2FsdGVkX183NevXMJZoomoUtaHd/hogzoJL9UFG3plljrYihfO5wjLyR2HW/lMlU7CTNARGjUgJUa+7LmAb0Yn6op/QB/hassWazpVm7Zt7dOIU7CUnGIWkLKK4LEbea/iEHqtbZjdjIxYefZZyiv+BfXfEHz6Sus54EuV1qo6yviMXFmIM10H6Za5YJ7PQ8XHmzkwuOGOJ2q/pbaPozCVBsUcZvDIUUTqxFyncVr90oD0jVX6QEWRfiHeOzoZrcjwLFl6ae0x7t08+py533f5oMC91JxZNOa7m2YoqvCF2+A7RFvqQfTXZuWnnXNofSYzmIUiCgEcc3+PzcLrDtCeiYGP+h78+nY7K1tFwD0MqOG+azXQmtLkoTPdgeuRyymIJXs6436T4SU3BKIbgxN97Qz73nTDgYADH9W0gdLrbC/7EpasbFMo4GQthbWxeM/z9OgORcpiaOyBksGxngWCNaCIwyjzsk0m2PdGWowp7PrN7wFTUSQSpFnfGslKBIUspeBJMBYi43mbPRSLpR/Fflb+tttrL7LhtS7/ZEFko8wEYUXzDtG0haQOcldm8t7CmTGial7RG5HBFM7zQhgKO7483bbASmmHVIOZtnQpf+8SU8jNbV2BhqkS0sAHvJtZH01CgzKtNHhz6jM/naU60CGFUmafrg/EpbC27a5G/cQ4VmhSEFQbfnFxUKyLTyQk/HyXB0O0sdAnqT2brZUC+whxmtNtcM1JqocPWjDb6S1BqE3vYpkrLi4VkwB1PttkZqS7cVfig7AcI3c//UlUzMD6/upg7EVivDhmhxVLxvTL034Y0IYhwHJj4xbc1B+Xnejc+C2blfue54CBWB9KEQ2KjVr8W6ZFllRYAMzQyCxS83vCXWPbCwTYxbppPLZ4to+2qCGoMJPA1vEtK6jq7P9ZRq+v3QlNS64zZC9RBF7rwNpjTmIxFIPnB5QurkdOMMgqvOp/IDXKQNCn LEf9NNv4 cyCfZ 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: List-Subscribe: List-Unsubscribe: On Sun, 28 Apr 2024 21:04:50 -0700 Luis Chamberlain wrote: > On Thu, Apr 25, 2024 at 02:01:26PM -0700, Andrew Morton wrote: > > On Wed, 24 Apr 2024 15:54:48 -0700 Luis Chamberlain wrote: > > > > > If the file entry is too long we may easily end up going out of bounds > > > and crash after strsep() on sscanf(). > > > > > > > Can you explain why? I'm not seeing it. > > I couldn't see it either but I just looked at the crash below and > its the only thing I could think of. So I think its when userspace > somehow abuses MAX_INPUT_BUF_SZ a lot somehow. This isn't a good basis for making kernel changes :( Can you investigate a little further please? What actually is present at *buf when your new checks succeed? Could we be seeing 0xNNN,0xNNN and leaving new_order unaltered? Or something.