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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 4D93FC5B57D for ; Wed, 3 Jul 2019 02:07:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DE742184B for ; Wed, 3 Jul 2019 02:07:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727354AbfGCCHM (ORCPT ); Tue, 2 Jul 2019 22:07:12 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:8128 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726329AbfGCCHM (ORCPT ); Tue, 2 Jul 2019 22:07:12 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 457DCBC5A1295040C698; Wed, 3 Jul 2019 10:07:10 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.214) with Microsoft SMTP Server (TLS) id 14.3.439.0; Wed, 3 Jul 2019 10:07:03 +0800 Subject: Re: [PATCH v2] f2fs: avoid out-of-range memory access To: Ocean Chen , , , References: <20190702080503.175149-1-oceanchen@google.com> From: Chao Yu Message-ID: Date: Wed, 3 Jul 2019 10:07:11 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190702080503.175149-1-oceanchen@google.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ocean, If filesystem is corrupted, it should fail mount due to below check in f2fs_sanity_check_ckpt(), so we are safe in read_compacted_summaries() to access entries[0,blk_off], right? for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) { if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs || le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg) return 1; Thanks, On 2019/7/2 16:05, Ocean Chen wrote: > blk_off might over 512 due to fs corrupt. > Use ENTRIES_IN_SUM to protect invalid memory access. > > v2: > - fix typo > Signed-off-by: Ocean Chen > --- > fs/f2fs/segment.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 8dee063c833f..a5e8af0bd62e 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi) > > for (j = 0; j < blk_off; j++) { > struct f2fs_summary *s; > + if (j >= ENTRIES_IN_SUM) > + return -EFAULT; > s = (struct f2fs_summary *)(kaddr + offset); > seg_i->sum_blk->entries[j] = *s; > offset += SUMMARY_SIZE; >