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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 B6BF7C6377A for ; Mon, 19 Jul 2021 16:24:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A14F26162A for ; Mon, 19 Jul 2021 16:24:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344045AbhGSPnW (ORCPT ); Mon, 19 Jul 2021 11:43:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:36334 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240971AbhGSPhh (ORCPT ); Mon, 19 Jul 2021 11:37:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A237360FD7; Mon, 19 Jul 2021 16:18:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626711484; bh=hDDzD76JYwZ7g0zfOG+sNBZgxh+bdim46FIsql9f0Zo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bFMACrlq0yZjnEWrK6aBK+y0qEJ0tG3iHhwgrQSTokISkun5Mi9Px7+XeBQD3iu79 OhLHJqKqtQ2tzkHwMgjmIpmUfV14XYghu4ajP7d1wFAnKuQa1KUhboy7Cvwfm4vNB5 7XVseBPxDvdh3QbnmnAxZDpB2BqhOcO5ItpbffFY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+a3fcd59df1b372066f5a@syzkaller.appspotmail.com, Joao Martins , Mike Kravetz , Andrew Morton , Linus Torvalds Subject: [PATCH 5.12 020/292] mm/hugetlb: fix refs calculation from unaligned @vaddr Date: Mon, 19 Jul 2021 16:51:22 +0200 Message-Id: <20210719144943.196978800@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144942.514164272@linuxfoundation.org> References: <20210719144942.514164272@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Joao Martins commit d08af0a59684e18a51aa4bfd24c658994ea3fc5b upstream. 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -5029,8 +5029,9 @@ 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),