From nobody Sun Oct 5 23:56:11 2025 Received: from mailout4.samsung.com (mailout4.samsung.com [203.254.224.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC4141547E7 for ; Mon, 28 Jul 2025 10:04:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.34 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753697085; cv=none; b=pIH7w2TWSlhmadghAqvia6fPAQwiK8+3p5Prt6sS4VuuZjZPvK9iqvZtgGJ5FbF4A1wdpWbTA3lOtAyHWCvjP4WkqKFB5J87RSncMquFbUXg9f14NDjV4SJyhnZNJ97qRzPrz08NtNCAvDeZ4tYrEa72/bld3gGAKjdOp0yCK6A= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753697085; c=relaxed/simple; bh=LJVLyxgyABlXHpYw153VKEv/B5Eal91bab73K3/yBIo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:Content-Type: References; b=d/542E34zup1sbKnuteeFbqRWt4250DYYi29ONd22h4iyu2i3XJsSUhS1OyreDRkCJ0Poc9SqDYF1Y0NEbd8WKf5sdQPqVfwn0ZtrO0KEjE7oh6OczQFDDAF8qYMpRQaJBDubHLmQb4snsFFS5yYR56N2K7MM6v6ccZ8K1w9038= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=pri0AUEN; arc=none smtp.client-ip=203.254.224.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="pri0AUEN" Received: from epcas5p2.samsung.com (unknown [182.195.41.40]) by mailout4.samsung.com (KnoxPortal) with ESMTP id 20250728100435epoutp0424d21b6f9046878b727592846be68468~WYjLO3mo32573225732epoutp04Q for ; Mon, 28 Jul 2025 10:04:35 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout4.samsung.com 20250728100435epoutp0424d21b6f9046878b727592846be68468~WYjLO3mo32573225732epoutp04Q DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1753697075; bh=J9ZLlX2aSkwMcC5wFXnqoLTWTC5wxs/G49Rac37NqYM=; h=From:To:Cc:Subject:Date:References:From; b=pri0AUENRvd4rdKedtZmXaAbPzRDxVHYAvYlFHx170JAWvTI/uRZkih3dn7YI6x2N HmP8MYmTMUjvBNC6gYQrbYru4hJn7iZZ00yM1yfsRAT3LaW87/KiL9C46g53Kf5jY8 oMRCT4UTQ/k6B+dP9H9kELKRiWXMI4lQO6XkjNP0= Received: from epsnrtp03.localdomain (unknown [182.195.42.155]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPS id 20250728100434epcas5p3c986696b00e17c6e513a4883209fd9e0~WYjKekBPG1620016200epcas5p3-; Mon, 28 Jul 2025 10:04:34 +0000 (GMT) Received: from epcas5p3.samsung.com (unknown [182.195.41.41]) by epsnrtp03.localdomain (Postfix) with ESMTP id 4brDbk2jn3z3hhTB; Mon, 28 Jul 2025 10:04:34 +0000 (GMT) Received: from epsmtip2.samsung.com (unknown [182.195.34.31]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPA id 20250728100434epcas5p3995d3444fcec14715c60f73e7a60b1c0~WYjKRMyrh1618416184epcas5p3m; Mon, 28 Jul 2025 10:04:34 +0000 (GMT) Received: from dl380gen10.. (unknown [109.120.22.112]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250728100433epsmtip23ee8525d47871ff2ceb5e39bd2f6d9f3~WYjJ4P88_2723727237epsmtip2I; Mon, 28 Jul 2025 10:04:33 +0000 (GMT) From: Jiufei Xue To: tj@kernel.org, jack@suse.cz Cc: cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jiufei Xue Subject: [PATCH] fs: writeback: fix use-after-free in __mark_inode_dirty() Date: Mon, 28 Jul 2025 18:07:15 +0800 Message-ID: <20250728100715.3863241-1-jiufei.xue@samsung.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CMS-MailID: 20250728100434epcas5p3995d3444fcec14715c60f73e7a60b1c0 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P X-CMS-RootMailID: 20250728100434epcas5p3995d3444fcec14715c60f73e7a60b1c0 References: An use-after-free issue occurred when __mark_inode_dirty() get the bdi_writeback that was in the progress of switching. CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1 ...... pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=3D--) pc : __mark_inode_dirty+0x124/0x418 lr : __mark_inode_dirty+0x118/0x418 sp : ffffffc08c9dbbc0 ........ Call trace: __mark_inode_dirty+0x124/0x418 generic_update_time+0x4c/0x60 file_modified+0xcc/0xd0 ext4_buffered_write_iter+0x58/0x124 ext4_file_write_iter+0x54/0x704 vfs_write+0x1c0/0x308 ksys_write+0x74/0x10c __arm64_sys_write+0x1c/0x28 invoke_syscall+0x48/0x114 el0_svc_common.constprop.0+0xc0/0xe0 do_el0_svc+0x1c/0x28 el0_svc+0x40/0xe4 el0t_64_sync_handler+0x120/0x12c el0t_64_sync+0x194/0x198 Root cause is: systemd-random-seed kworker Reviewed-by: Jan Kara ---------------------------------------------------------------------- ___mark_inode_dirty inode_switch_wbs_work_fn spin_lock(&inode->i_lock); inode_attach_wb locked_inode_to_wb_and_lock_list get inode->i_wb spin_unlock(&inode->i_lock); spin_lock(&wb->list_lock) spin_lock(&inode->i_lock) inode_io_list_move_locked spin_unlock(&wb->list_lock) spin_unlock(&inode->i_lock) spin_lock(&old_wb->list_lock) inode_do_switch_wbs spin_lock(&inode->i_lock) inode->i_wb =3D new_wb spin_unlock(&inode->i_lock) spin_unlock(&old_wb->list_lock) wb_put_many(old_wb, nr_switched) cgwb_release old wb released wb_wakeup_delayed() accesses wb, then trigger the use-after-free issue Fix this race condition by holding inode spinlock until wb_wakeup_delayed() finished. Signed-off-by: Jiufei Xue --- fs/fs-writeback.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index cc57367fb..a07b8cf73 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -2608,10 +2608,6 @@ void __mark_inode_dirty(struct inode *inode, int fla= gs) wakeup_bdi =3D inode_io_list_move_locked(inode, wb, dirty_list); =20 - spin_unlock(&wb->list_lock); - spin_unlock(&inode->i_lock); - trace_writeback_dirty_inode_enqueue(inode); - /* * If this is the first dirty inode for this bdi, * we have to wake-up the corresponding bdi thread @@ -2621,6 +2617,11 @@ void __mark_inode_dirty(struct inode *inode, int fla= gs) if (wakeup_bdi && (wb->bdi->capabilities & BDI_CAP_WRITEBACK)) wb_wakeup_delayed(wb); + + spin_unlock(&wb->list_lock); + spin_unlock(&inode->i_lock); + trace_writeback_dirty_inode_enqueue(inode); + return; } } --=20 2.43.0