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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 7FDE7C433E0 for ; Wed, 17 Jun 2020 22:47:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 331FA20885 for ; Wed, 17 Jun 2020 22:47:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uBYpo0Vw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 331FA20885 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 916026B0008; Wed, 17 Jun 2020 18:47:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A07D6B000A; Wed, 17 Jun 2020 18:47:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7674E6B000C; Wed, 17 Jun 2020 18:47:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0228.hostedemail.com [216.40.44.228]) by kanga.kvack.org (Postfix) with ESMTP id 5C0226B0008 for ; Wed, 17 Jun 2020 18:47:27 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id AA61A180AD801 for ; Wed, 17 Jun 2020 22:47:26 +0000 (UTC) X-FDA: 76940191692.11.wheel06_2c16aaa26e0b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin11.hostedemail.com (Postfix) with ESMTP id 78F56180F8B82 for ; Wed, 17 Jun 2020 22:47:26 +0000 (UTC) X-HE-Tag: wheel06_2c16aaa26e0b X-Filterd-Recvd-Size: 2931 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Wed, 17 Jun 2020 22:47:25 +0000 (UTC) Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DEEDC20885; Wed, 17 Jun 2020 22:47:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592434045; bh=GuBEAyJbQnr0mMqGZwEJ3Eq1JvZWz9/H6Cpc9CBqpHQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uBYpo0VwLtxQfYmjHGoGYG2143Bfa2P5b85h+4Imij6SLLKLbvYZq8D4i19w1MrzO KrB/sLTItAv1rlR3p6wPbfLXV9OE9cHqoXEZLe2oO6zMbTQSpmcLjx06LMisahZ+Y/ /ZckaT/mIMGnPq4pQ1QubH4uU5+3Wekfrz+6a4w0= Date: Wed, 17 Jun 2020 15:47:24 -0700 From: Andrew Morton To: Kaiyu Zhang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/memory.c: make remap_pfn_range() reject unaligned addr Message-Id: <20200617154724.1b4d8a0353c7b8d0d7c79c0b@linux-foundation.org> In-Reply-To: <20200617223414.165923-1-zhangalex@google.com> References: <20200617223414.165923-1-zhangalex@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 78F56180F8B82 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Wed, 17 Jun 2020 15:34:14 -0700 Kaiyu Zhang wrote: > From: Alex Zhang > > This function implicitly assumes that the addr passed in is page aligned. > A non page aligned addr could ultimately cause a kernel bug in > remap_pte_range as the exit condition in the logic loop may never be > satisfied. This patch documents the need for the requirement, as > well as explicitly adding a check for it. > > ... > > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -2081,7 +2081,7 @@ static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, > /** > * remap_pfn_range - remap kernel memory to userspace > * @vma: user vma to map to > - * @addr: target user address to start at > + * @addr: target page aligned user address to start at > * @pfn: page frame number of kernel physical memory address > * @size: size of mapping area > * @prot: page protection flags for this mapping > @@ -2100,6 +2100,9 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, > unsigned long remap_pfn = pfn; > int err; > > + if (!PAGE_ALIGN(addr)) > + return -EINVAL; > + That won't work. PAGE_ALIGNED() will do so. Also, as this is an error in the calling code it would be better to do if (WARN_ON_ONCE(!PAGE_ALIGNED(addr))) return -EINVAL; so that the offending code can be fixed up. Is there any code in the kernel tree which actually has this error?