From patchwork Wed Jul 14 23:06:36 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 478343 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, SPF_PASS, URIBL_BLOCKED autolearn=unavailable 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 36DD3C1B08C for ; Wed, 14 Jul 2021 23:06:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F847613C9 for ; Wed, 14 Jul 2021 23:06:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230503AbhGNXJ3 (ORCPT ); Wed, 14 Jul 2021 19:09:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:34350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229928AbhGNXJ3 (ORCPT ); Wed, 14 Jul 2021 19:09:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B989C613C2; Wed, 14 Jul 2021 23:06:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1626303996; bh=B5mAT138Ng1LaI3gJo+9LuGhZ0vn0kN4sGUAme0cawY=; h=Date:From:To:Subject:From; b=P1byBgkDI6yHZh7llu3uEaivIWAoWWlMShIuldXtT5tl0hWIPMBnYcRBpNDNtWxnf BZXZOyxmz+6YywZfo1Px1JPV5lMga4W/j9GKZwIfPN+5Huil37AWd2+s6TbrKql+Ze 0jRtrB0ktYloqEzSSGYPhlhh4R2insHxOOTXLwI4= Date: Wed, 14 Jul 2021 16:06:36 -0700 From: akpm@linux-foundation.org To: joao.m.martins@oracle.com, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, stable@vger.kernel.org Subject: [to-be-updated] mm-hugetlb-fix-refs-calculation-from-unaligned-vaddr.patch removed from -mm tree Message-ID: <20210714230636.VSnmj4qe3%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm/hugetlb: fix refs calculation from unaligned @vaddr has been removed from the -mm tree. Its filename was mm-hugetlb-fix-refs-calculation-from-unaligned-vaddr.patch This patch was dropped because an updated version will be merged ------------------------------------------------------ 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),