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 C1144C352A1 for ; Sat, 3 Dec 2022 13:41:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229452AbiLCNlS (ORCPT ); Sat, 3 Dec 2022 08:41:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229730AbiLCNlH (ORCPT ); Sat, 3 Dec 2022 08:41:07 -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 1CD451E72C for ; Sat, 3 Dec 2022 05:41:04 -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 CCE66B80171 for ; Sat, 3 Dec 2022 13:41:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE19CC433C1; Sat, 3 Dec 2022 13:40:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1670074861; bh=lC3cJFofR+zhCmLhUsHeRFJ6ctKIcQkmqm79H+YLWlc=; h=Date:From:To:Subject:References:In-Reply-To:From; b=XH2wVCtJYOCFs6yyHoyLeHaMoThm7IW3y/yb+kk5N0EKl6Uqd+0U2VRdRHquXrNuT q8BwMWOL6tJfsHdNNCNVkAWCLhJ/92PecS45JNwjR45/PDVSNQ+R6SYOrJQTtXkyj3 zf5HDURt1VjLARMpIUN49JYWwobQ2WBL8+odTF0p2DTNZguaU9qP6nvdL1iPUE22Rs jKOFc+XB7AW7XFQwTX6AYIkLfrrkPZdKyB+gLPmbiQA8z8kDT5KwNTB2XvHLAbeagX I9QIKD52Zfg3O6bwIl2D4LjjcAxhcTEaHci55TbGDiDeOp7pdhULxGwRErT6DYWSHW 4/6hbYLwnulug== Date: Sat, 3 Dec 2022 21:40:55 +0800 From: Gao Xiang To: Chen Zhongjin , syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com, linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, xiang@kernel.org, chao@kernel.org, huyue2@coolpad.com, jefflexu@linux.alibaba.com Subject: Re: [PATCH] erofs: Fix pcluster become inline when m_pa is zero Message-ID: Mail-Followup-To: Chen Zhongjin , syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com, linux-erofs@lists.ozlabs.org, linux-kernel@vger.kernel.org, xiang@kernel.org, chao@kernel.org, huyue2@coolpad.com, jefflexu@linux.alibaba.com References: <20221203094527.129869-1-chenzhongjin@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 03, 2022 at 09:20:17PM +0800, Gao Xiang wrote: > Hi Zhongjin, > > On Sat, Dec 03, 2022 at 05:45:27PM +0800, Chen Zhongjin wrote: > > syzkaller reported a memleak: > > https://syzkaller.appspot.com/bug?id=62f37ff612f0021641eda5b17f056f1668aa9aed > > > > unreferenced object 0xffff88811009c7f8 (size 136): > > ... > > backtrace: > > [] z_erofs_do_read_page+0x99b/0x1740 > > [] z_erofs_readahead+0x24e/0x580 > > [] read_pages+0x86/0x3d0 > > ... > > > > syzkaller constructed a case: in z_erofs_register_pcluster(), > > ztailpacking = false and map->m_pa = zero. This makes pcl->obj.index > > become zero although pcl is not an inline pcluster. > > Thanks for the patch! > > We should just fail out if map->m_pa / EROFS_BLKSIZ == 0. > > > > > Then following path adds refcount for grp, but the it won't be put > > because pcl is inline, which makes pcl not released when shrink. > > > > z_erofs_readahead() > > z_erofs_do_read_page() # for another page > > z_erofs_collector_begin() > > erofs_find_workgroup() > > erofs_workgroup_get() > > > > To fix this, add an attribute in z_erofs_pcluster to mark the inline > > state which not depends on index of grp. > > I think the main reason is "inline pcluster _always_ did memory leak > before since I don't find any chance to these free inline pclusters > in the current codebase. > > Actually I submitted a patch for this, could you check/review this > if possible? > https://lore.kernel.org/r/20221202033327.52702-1-hsiangkao@linux.alibaba.com Oh, I just realized my patch may be incorrect, I think we need to just fail out this (since m_pblk == 0 cannot be a real pcluster, since it has on-disk super block at least): diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index ab22100be861..e14e6c32e70d 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -496,7 +496,8 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe) struct erofs_workgroup *grp; int err; - if (!(map->m_flags & EROFS_MAP_ENCODED)) { + if (!(map->m_flags & EROFS_MAP_ENCODED) || + !(map->m_pa >> PAGE_SHIFT)) { DBG_BUGON(1); return -EFSCORRUPTED; Could you resend next version behaving like the above? Thanks, Gao Xiang > > Thanks, > Gao Xiang > > > > > Fixes: cecf864d3d76 ("erofs: support inline data decompression") > > Reported-by: syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com > > Signed-off-by: Chen Zhongjin > > --- > > fs/erofs/zdata.c | 2 +- > > fs/erofs/zdata.h | 5 ++++- > > 2 files changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c > > index b792d424d774..fef2624d19e3 100644 > > --- a/fs/erofs/zdata.c > > +++ b/fs/erofs/zdata.c > > @@ -517,7 +517,7 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe) > > DBG_BUGON(!mutex_trylock(&pcl->lock)); > > > > if (ztailpacking) { > > - pcl->obj.index = 0; /* which indicates ztailpacking */ > > + pcl->is_inline = true; /* which indicates ztailpacking */ > > pcl->pageofs_in = erofs_blkoff(map->m_pa); > > pcl->tailpacking_size = map->m_plen; > > } else { > > diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h > > index d98c95212985..35051ad27521 100644 > > --- a/fs/erofs/zdata.h > > +++ b/fs/erofs/zdata.h > > @@ -78,6 +78,9 @@ struct z_erofs_pcluster { > > unsigned short tailpacking_size; > > }; > > > > + /* I: whether it is inline or not */ > > + bool is_inline; > > + > > /* I: compression algorithm format */ > > unsigned char algorithmformat; > > > > @@ -115,7 +118,7 @@ struct z_erofs_decompressqueue { > > > > static inline bool z_erofs_is_inline_pcluster(struct z_erofs_pcluster *pcl) > > { > > - return !pcl->obj.index; > > + return pcl->is_inline; > > } > > > > static inline unsigned int z_erofs_pclusterpages(struct z_erofs_pcluster *pcl) > > -- > > 2.17.1 > >