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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE autolearn=ham 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 E128FC47E48 for ; Thu, 15 Jul 2021 04:27:13 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9C688613A9 for ; Thu, 15 Jul 2021 04:27:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C688613A9 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 EC0EB6B0154; Thu, 15 Jul 2021 00:27:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E967B6B0156; Thu, 15 Jul 2021 00:27:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D382E6B0157; Thu, 15 Jul 2021 00:27:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0171.hostedemail.com [216.40.44.171]) by kanga.kvack.org (Postfix) with ESMTP id B2A556B0154 for ; Thu, 15 Jul 2021 00:27:13 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id B007B2203E for ; Thu, 15 Jul 2021 04:27:12 +0000 (UTC) X-FDA: 78363537504.18.3712512 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf23.hostedemail.com (Postfix) with ESMTP id 637FA9000701 for ; Thu, 15 Jul 2021 04:27:12 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 716DC613B2; Thu, 15 Jul 2021 04:27:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1626323231; bh=9m0k110N20kOAoP/o62BcYLkYEF1k7ZEGkRxpN1LxW4=; h=Date:From:To:Subject:In-Reply-To:From; b=Jxns9f0nh5iFonmRirk9p1rMWpQ+Q8m7zXlPLCYUGL//VCSWxpTAJiEJmFPXEioiC KP+PVX0tU8FukAljXxcH4D3djtQiklr87Z4NLuNEjiMj0U+YhMDbdfxm/3KsyAhyPD odUbbxsCY7f7uj5pKTT21j3IYnMNvUrfi/cmwNeA= Date: Wed, 14 Jul 2021 21:27:11 -0700 From: Andrew Morton To: akpm@linux-foundation.org, joao.m.martins@oracle.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 13/13] mm/hugetlb: fix refs calculation from unaligned @vaddr Message-ID: <20210715042711.DQ8aY7BZt%akpm@linux-foundation.org> In-Reply-To: <20210714212609.fad116e584ba1194981a6294@linux-foundation.org> User-Agent: s-nail v14.8.16 Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=Jxns9f0n; spf=pass (imf23.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 637FA9000701 X-Stat-Signature: xwm3kx4qaikmnmhaynbgwfzw3q3zcrkd X-HE-Tag: 1626323232-636111 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: From: Joao Martins Subject: mm/hugetlb: fix refs calculation from unaligned @vaddr commit 82e5d378b0e47 ("mm/hugetlb: refactor subpage recording") refactored the count of subpages but missed an edge case when @vaddr is not aligned to PAGE_SIZE e.g. when close to vma->vm_end. It would then errousnly set @refs to 0 and record_subpages_vmas() wouldn't set the @pages array element to its value, consequently causing the reported null-deref by syzbot. Fix it by aligning down @vaddr by PAGE_SIZE in @refs calculation. Link: https://lkml.kernel.org/r/20210713152440.28650-1-joao.m.martins@oracle.com Fixes: 82e5d378b0e47 ("mm/hugetlb: refactor subpage recording") Reported-by: syzbot+a3fcd59df1b372066f5a@syzkaller.appspotmail.com Signed-off-by: Joao Martins Reviewed-by: Mike Kravetz Cc: Signed-off-by: Andrew Morton --- mm/hugetlb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/hugetlb.c~mm-hugetlb-fix-refs-calculation-from-unaligned-vaddr +++ a/mm/hugetlb.c @@ -5440,8 +5440,9 @@ long follow_hugetlb_page(struct mm_struc continue; } - refs = min3(pages_per_huge_page(h) - pfn_offset, - (vma->vm_end - vaddr) >> PAGE_SHIFT, remainder); + /* vaddr may not be aligned to PAGE_SIZE */ + refs = min3(pages_per_huge_page(h) - pfn_offset, remainder, + (vma->vm_end - ALIGN_DOWN(vaddr, PAGE_SIZE)) >> PAGE_SHIFT); if (pages || vmas) record_subpages_vmas(mem_map_offset(page, pfn_offset), _