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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A7CDC61DA4 for ; Fri, 3 Feb 2023 22:15:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229785AbjBCWPO (ORCPT ); Fri, 3 Feb 2023 17:15:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233357AbjBCWOq (ORCPT ); Fri, 3 Feb 2023 17:14:46 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEEC1AF50D for ; Fri, 3 Feb 2023 14:13:48 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9EA26B82C2A for ; Fri, 3 Feb 2023 22:13:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E596C433D2; Fri, 3 Feb 2023 22:13:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1675462426; bh=1iWzk2KavpLoJK5p82ahS7/RHM/4/fObC7e3mL6ywA8=; h=Date:To:From:Subject:From; b=vuklxjO7FuP09D9iDd8A60HLR6numhAQoTE3kPZ0NfYazEwk48v0ijliweAaNt87A rJYMRLlNjSFZdkE9pDj4SFJe3ASDpu1rn3CBIal0oEIa4xLps0dB/R8F17I8RvE7Nt iDdZX4zbN0N0T8/eotLMO66U/mevqZ8lsp0Xbq4k= Date: Fri, 03 Feb 2023 14:13:45 -0800 To: mm-commits@vger.kernel.org, ira.weiny@intel.com, fmdefrancesco@gmail.com, willy@infradead.org, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-add-memcpy_from_file_folio.patch added to mm-unstable branch Message-Id: <20230203221346.3E596C433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm: fix memcpy_from_file_folio() integer underflow has been added to the -mm mm-unstable branch. Its filename is mm-add-memcpy_from_file_folio.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-add-memcpy_from_file_folio.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: "Matthew Wilcox (Oracle)" Subject: mm: fix memcpy_from_file_folio() integer underflow Date: Fri, 3 Feb 2023 16:28:40 -0500 If we have a HIGHMEM system with a large folio, 'offset' may be larger than PAGE_SIZE, and so min_t will cap at 'len' instead of the intended end-of-page. That can overflow into the next page which is likely to be unmapped and fault, but could theoretically copy the wrong data. Link: https://lkml.kernel.org/r/Y919vmSrtAgsf6K3@casper.infradead.org Fixes: 00cdf76012ab ("mm: add memcpy_from_file_folio()") Signed-off-by: Matthew Wilcox (Oracle) Cc: "Fabio M. De Francesco" Cc: Ira Weiny Signed-off-by: Andrew Morton --- --- a/include/linux/highmem.h~mm-add-memcpy_from_file_folio +++ a/include/linux/highmem.h @@ -431,9 +431,10 @@ static inline size_t memcpy_from_file_fo size_t offset = offset_in_folio(folio, pos); char *from = kmap_local_folio(folio, offset); - if (folio_test_highmem(folio)) + if (folio_test_highmem(folio)) { + offset = offset_in_page(offset); len = min_t(size_t, len, PAGE_SIZE - offset); - else + } else len = min(len, folio_size(folio) - offset); memcpy(to, from, len); _ Patches currently in -mm which might be from willy@infradead.org are mm-add-memcpy_from_file_folio.patch