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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 DE5A7C47247 for ; Tue, 5 May 2020 14:11:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD5132073B for ; Tue, 5 May 2020 14:11:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="XdlMGnT4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728749AbgEEOLu (ORCPT ); Tue, 5 May 2020 10:11:50 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:54905 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727857AbgEEOLu (ORCPT ); Tue, 5 May 2020 10:11:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588687906; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ykJo/xcYZHgKYXRosI/v2AxHguK/RFl/7PBSFi2snpg=; b=XdlMGnT4Q4X0RzvoeafJA2OlsmLUXQwYr2kgeP1hi+ccbm+XbPvVYJElpDZpQ9lMqBtyS3 J3hJ99Aj+J/s7H/yK4n5EHJ0IPodYDwXh3sZVJB0zv9E/qhZUJHLkS1PHs7OcCTUDIgyYR fZJVnnAcgsWUcqf/7qhcCN0yQKWIzUw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-287-SH76wt4FM4Odbg3CRG7bng-1; Tue, 05 May 2020 10:11:42 -0400 X-MC-Unique: SH76wt4FM4Odbg3CRG7bng-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 400C51800D4A; Tue, 5 May 2020 14:11:41 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C297A60BEC; Tue, 5 May 2020 14:11:40 +0000 (UTC) Date: Tue, 5 May 2020 10:11:38 -0400 From: Brian Foster To: "Darrick J. Wong" Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 3/3] xfs: fix an incore inode UAF in xfs_bui_recover Message-ID: <20200505141138.GB61176@bfoster> References: <158864121286.184729.5959003885146573075.stgit@magnolia> <158864123329.184729.14504239314355330619.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <158864123329.184729.14504239314355330619.stgit@magnolia> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Mon, May 04, 2020 at 06:13:53PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > In xfs_bui_item_recover, there exists a use-after-free bug with regards > to the inode that is involved in the bmap replay operation. If the > mapping operation does not complete, we call xfs_bmap_unmap_extent to > create a deferred op to finish the unmapping work, and we retain a > pointer to the incore inode. > > Unfortunately, the very next thing we do is commit the transaction and > drop the inode. If reclaim tears down the inode before we try to finish > the defer ops, we dereference garbage and blow up. Therefore, create a > way to join inodes to the defer ops freezer so that we can maintain the > xfs_inode reference until we're done with the inode. > > Note: This imposes the requirement that there be enough memory to keep > every incore inode in memory throughout recovery. > > Signed-off-by: Darrick J. Wong > --- Maybe I'm missing something, but I thought the discussion on the previous version[1] landed on an approach where the intent would hold a reference to the inode. Wouldn't that break the dependency on the dfops freeze/thaw mechanism? Brian [1] https://lore.kernel.org/linux-xfs/20200429235818.GX6742@magnolia/ > fs/xfs/libxfs/xfs_defer.c | 50 +++++++++++++++++++++++++++++++++++++++++++++ > fs/xfs/libxfs/xfs_defer.h | 10 +++++++++ > fs/xfs/xfs_bmap_item.c | 7 ++++-- > fs/xfs/xfs_icache.c | 19 +++++++++++++++++ > 4 files changed, 83 insertions(+), 3 deletions(-) > > > diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c > index ea4d28851bbd..72933fdafcb2 100644 > --- a/fs/xfs/libxfs/xfs_defer.c > +++ b/fs/xfs/libxfs/xfs_defer.c > @@ -16,6 +16,7 @@ > #include "xfs_inode.h" > #include "xfs_inode_item.h" > #include "xfs_trace.h" > +#include "xfs_icache.h" > > /* > * Deferred Operations in XFS > @@ -583,8 +584,19 @@ xfs_defer_thaw( > struct xfs_defer_freezer *dff, > struct xfs_trans *tp) > { > + int i; > + > ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES); > > + /* Re-acquire the inode locks. */ > + for (i = 0; i < XFS_DEFER_FREEZER_INODES; i++) { > + if (!dff->dff_inodes[i]) > + break; > + > + dff->dff_ilocks[i] = XFS_ILOCK_EXCL; > + xfs_ilock(dff->dff_inodes[i], dff->dff_ilocks[i]); > + } > + > /* Add the dfops items to the transaction. */ > list_splice_init(&dff->dff_dfops, &tp->t_dfops); > tp->t_flags |= dff->dff_tpflags; > @@ -597,5 +609,43 @@ xfs_defer_freeezer_finish( > struct xfs_defer_freezer *dff) > { > xfs_defer_cancel_list(mp, &dff->dff_dfops); > + xfs_defer_freezer_irele(dff); > kmem_free(dff); > } > + > +/* > + * Attach an inode to this deferred ops freezer. Callers must hold ILOCK_EXCL, > + * which will be dropped and reacquired when we're ready to thaw the frozen > + * deferred ops. > + */ > +int > +xfs_defer_freezer_ijoin( > + struct xfs_defer_freezer *dff, > + struct xfs_inode *ip) > +{ > + unsigned int i; > + > + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); > + > + for (i = 0; i < XFS_DEFER_FREEZER_INODES; i++) { > + if (dff->dff_inodes[i] == ip) > + goto out; > + if (dff->dff_inodes[i] == NULL) > + break; > + } > + > + if (i == XFS_DEFER_FREEZER_INODES) { > + ASSERT(0); > + return -EFSCORRUPTED; > + } > + > + /* > + * Attach this inode to the freezer and drop its ILOCK because we > + * assume the caller will need to allocate a transaction. > + */ > + dff->dff_inodes[i] = ip; > + dff->dff_ilocks[i] = 0; > +out: > + xfs_iunlock(ip, XFS_ILOCK_EXCL); > + return 0; > +} > diff --git a/fs/xfs/libxfs/xfs_defer.h b/fs/xfs/libxfs/xfs_defer.h > index 7ae05e10d750..0052a0313283 100644 > --- a/fs/xfs/libxfs/xfs_defer.h > +++ b/fs/xfs/libxfs/xfs_defer.h > @@ -76,6 +76,11 @@ struct xfs_defer_freezer { > /* Deferred ops state saved from the transaction. */ > struct list_head dff_dfops; > unsigned int dff_tpflags; > + > + /* Inodes to hold when we want to finish the deferred work items. */ > +#define XFS_DEFER_FREEZER_INODES 2 > + unsigned int dff_ilocks[XFS_DEFER_FREEZER_INODES]; > + struct xfs_inode *dff_inodes[XFS_DEFER_FREEZER_INODES]; > }; > > /* Functions to freeze a chain of deferred operations for later. */ > @@ -83,5 +88,10 @@ int xfs_defer_freeze(struct xfs_trans *tp, struct xfs_defer_freezer **dffp); > void xfs_defer_thaw(struct xfs_defer_freezer *dff, struct xfs_trans *tp); > void xfs_defer_freeezer_finish(struct xfs_mount *mp, > struct xfs_defer_freezer *dff); > +int xfs_defer_freezer_ijoin(struct xfs_defer_freezer *dff, > + struct xfs_inode *ip); > + > +/* These functions must be provided by the xfs implementation. */ > +void xfs_defer_freezer_irele(struct xfs_defer_freezer *dff); > > #endif /* __XFS_DEFER_H__ */ > diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c > index c733bdeeeb9b..bbce191d8fcd 100644 > --- a/fs/xfs/xfs_bmap_item.c > +++ b/fs/xfs/xfs_bmap_item.c > @@ -530,12 +530,13 @@ xfs_bui_item_recover( > } > > error = xlog_recover_trans_commit(tp, dffp); > - xfs_iunlock(ip, XFS_ILOCK_EXCL); > - xfs_irele(ip); > - return error; > + if (error) > + goto err_rele; > + return xfs_defer_freezer_ijoin(*dffp, ip); > > err_inode: > xfs_trans_cancel(tp); > +err_rele: > if (ip) { > xfs_iunlock(ip, XFS_ILOCK_EXCL); > xfs_irele(ip); > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > index 17a0b86fe701..b96ddf5ff334 100644 > --- a/fs/xfs/xfs_icache.c > +++ b/fs/xfs/xfs_icache.c > @@ -12,6 +12,7 @@ > #include "xfs_sb.h" > #include "xfs_mount.h" > #include "xfs_inode.h" > +#include "xfs_defer.h" > #include "xfs_trans.h" > #include "xfs_trans_priv.h" > #include "xfs_inode_item.h" > @@ -1847,3 +1848,21 @@ xfs_start_block_reaping( > xfs_queue_eofblocks(mp); > xfs_queue_cowblocks(mp); > } > + > +/* Release all the inode resources attached to this freezer. */ > +void > +xfs_defer_freezer_irele( > + struct xfs_defer_freezer *dff) > +{ > + unsigned int i; > + > + for (i = 0; i < XFS_DEFER_FREEZER_INODES; i++) { > + if (!dff->dff_inodes[i]) > + break; > + > + if (dff->dff_ilocks[i]) > + xfs_iunlock(dff->dff_inodes[i], dff->dff_ilocks[i]); > + xfs_irele(dff->dff_inodes[i]); > + dff->dff_inodes[i] = NULL; > + } > +} >