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 D7B14C433EF for ; Wed, 19 Jan 2022 13:28:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1CE4E6B0071; Wed, 19 Jan 2022 08:28:23 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 17A566B0073; Wed, 19 Jan 2022 08:28:23 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 040D46B0074; Wed, 19 Jan 2022 08:28:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0205.hostedemail.com [216.40.44.205]) by kanga.kvack.org (Postfix) with ESMTP id E3C316B0071 for ; Wed, 19 Jan 2022 08:28:22 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 97DDF181F598F for ; Wed, 19 Jan 2022 13:28:22 +0000 (UTC) X-FDA: 79047115644.07.9C05F50 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf04.hostedemail.com (Postfix) with ESMTP id 047EF4002E for ; Wed, 19 Jan 2022 13:28:21 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 00E38ED1; Wed, 19 Jan 2022 05:28:21 -0800 (PST) Received: from [10.57.67.190] (unknown [10.57.67.190]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 1F94E3F73D; Wed, 19 Jan 2022 05:28:18 -0800 (PST) Message-ID: Date: Wed, 19 Jan 2022 13:28:14 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH] vmap(): don't allow invalid pages Content-Language: en-GB To: Yury Norov , Catalin Marinas , Will Deacon , Andrew Morton , Nicholas Piggin , Ding Tianhong , Anshuman Khandual , Matthew Wilcox , Alexey Klimov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20220118235244.540103-1-yury.norov@gmail.com> From: Robin Murphy In-Reply-To: <20220118235244.540103-1-yury.norov@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: okq7cfp43u5rqqbpda7i3j5d35gnigxg Authentication-Results: imf04.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=arm.com; spf=pass (imf04.hostedemail.com: domain of robin.murphy@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=robin.murphy@arm.com X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 047EF4002E X-HE-Tag: 1642598901-257620 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 2022-01-18 23:52, Yury Norov wrote: > vmap() takes struct page *pages as one of arguments, and user may provide > an invalid pointer which would lead to DABT at address translation later. > > Currently, kernel checks the pages against NULL. In my case, however, the > address was not NULL, and was big enough so that the hardware generated > Address Size Abort on arm64. > > Interestingly, this abort happens even if copy_from_kernel_nofault() is > used, which is quite inconvenient for debugging purposes. > > This patch adds a pfn_valid() check into vmap() path, so that invalid > mapping will not be created. > > RFC: https://lkml.org/lkml/2022/1/18/815 > v1: use pfn_valid() instead of adding an arch-specific > arch_vmap_page_valid(). Thanks to Matthew Wilcox for the hint. > > Signed-off-by: Yury Norov > --- > mm/vmalloc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d2a00ad4e1dd..a4134ee56b10 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -477,6 +477,8 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, > return -EBUSY; > if (WARN_ON(!page)) > return -ENOMEM; > + if (WARN_ON(!pfn_valid(page_to_pfn(page)))) Is it page_to_pfn() guaranteed to work without blowing up if page is invalid in the first place? Looking at the CONFIG_SPARSEMEM case I'm not sure that's true... Robin. > + return -EINVAL; > set_pte_at(&init_mm, addr, pte, mk_pte(page, prot)); > (*nr)++; > } while (pte++, addr += PAGE_SIZE, addr != end);