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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 54480C433EF for ; Wed, 19 Jan 2022 06:18:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=Ptc2HH+1ZfRErBgl7OEKCKlTJ9MwqhBqbKV6ANLVazw=; b=QkvWggeQH7oAJzOGFylVIlYN0e en0diZ0wl77m6SgTBKcNX7eAl+MSJHAe7DdSZqPeVTEX2SzdOcP2QcxlSleWAF/UNRRvA/7dd8LX+ w3yyOAUBsm38txKYs1jcBym+SKCnBRoctifDNDDW9nQkHLUxmjdWzDLLU+Ekf4mm0Lkjlo0QV65lF wwRSqbWnAaSWp5iZhFn+vOuF+MW9wPiGRxMDzved2zmfAZB/njXve4083X7kvppgxjMg2xurW1wMd 9flT8LtVV1yexRF10tLCR0OtJEPRie4YVHVbZf7MoybU96sl3EYVC2nf3WuLwBfvRbR3MiYo/rfpL b46t54/Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nA4Hg-003vp5-CQ; Wed, 19 Jan 2022 06:17:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nA4Hc-003vnb-1e for linux-arm-kernel@lists.infradead.org; Wed, 19 Jan 2022 06:17:25 +0000 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 4898FD6E; Tue, 18 Jan 2022 22:17:19 -0800 (PST) Received: from [10.163.74.69] (unknown [10.163.74.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3F7143F73D; Tue, 18 Jan 2022 22:17:14 -0800 (PST) Subject: Re: [PATCH] vmap(): don't allow invalid pages To: Matthew Wilcox , Yury Norov Cc: Catalin Marinas , Will Deacon , Andrew Morton , Nicholas Piggin , Ding Tianhong , Alexey Klimov , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Uladzislau Rezki References: <20220118235244.540103-1-yury.norov@gmail.com> From: Anshuman Khandual Message-ID: Date: Wed, 19 Jan 2022 11:47:18 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220118_221724_180213_71D5EECA X-CRM114-Status: GOOD ( 18.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 1/19/22 6:21 AM, Matthew Wilcox wrote: > On Tue, Jan 18, 2022 at 03:52:44PM -0800, 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. > > Could we spell out 'DABT'? Presumably that's an ARM-specific thing. > Just like we don't say #PF for Intel page faults, I think this is > probably a 'data abort'? Right, it is data abort. > >> 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. Could you please provide the actual abort stack here with details. >> >> 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. This should be after the '---' below. >> >> Signed-off-by: Yury Norov > > Suggested-by: Matthew Wilcox (Oracle) > >> --- >> 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)))) >> + return -EINVAL; >> set_pte_at(&init_mm, addr, pte, mk_pte(page, prot)); >> (*nr)++; >> } while (pte++, addr += PAGE_SIZE, addr != end); >> -- >> 2.30.2 >> Why should not this just scan over the entire user provided struct page array and make sure that all pages there in are valid via above method, but in vmap() itself before calling vmap_pages_range(). Because seems like a single invalid page detected in vmap_pages_pte_range() will anyways abort the entire vmap(). This will also enable us to drop the existing NULL check above. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel