From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout02.his.huawei.com (canpmsgout02.his.huawei.com [113.46.200.217]) (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 10A652ECE96 for ; Wed, 22 Oct 2025 08:01:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.217 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761120072; cv=none; b=moDM2XhP6hfLZHWgj+8LY7yQLBCCA5ayItlE9+DXO84mYjyq7iY/UAAPfESHavzYzmqOPSXu33wKxXRqJOYvcbSQ3RMHoaAwex2TCAEFCEHswEbUqNaY45PMEHFnLJgyXQJcEi6SxMhFGzJmc3GkY6cNAkGnfEYAGLkfgt5HGiA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761120072; c=relaxed/simple; bh=vsa6P2uLnA2Y2ShzeP0pbEL2qU+RWBEMC6rPSsR+OaQ=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=rTZSfagarIorgwcWB2IfSijfMP1C4ahpwkKByJAVjpLY23LT7/6GNdMRhnoHlCMcedRJI+P/AxnuAZZ9uqmGw+LXnETYeEQo6gw3Mdgr+iov24mZm2UFqvzNzYY2JJgC941gucQGfRpAuJXqraGMfpCY4FFVc7aBPuewNkbF8eQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=wJZvgD0/; arc=none smtp.client-ip=113.46.200.217 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="wJZvgD0/" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=V433eXoxEudPslw3dRmuPlZIQVWnFsjfLzgNyoahat4=; b=wJZvgD0/gOY+GfD/ykd8BsZK1AOA55dSL5nhG7VbROw0/v7C+ld/4OC48mPTcwJf3jcKFvuks gVatLrojquMP2XluYo6g6mE6UVcgs3H0QVuTewKhxoT1Pf62/ftZaEahtAoVPH3tX2gWT2r6vGI fR1/54ErKWdeH+LEaZ/EMw0= Received: from mail.maildlp.com (unknown [172.19.163.252]) by canpmsgout02.his.huawei.com (SkyGuard) with ESMTPS id 4cs1mB2G4lzcb2f; Wed, 22 Oct 2025 15:59:54 +0800 (CST) Received: from kwepemj200013.china.huawei.com (unknown [7.202.194.25]) by mail.maildlp.com (Postfix) with ESMTPS id 4F045180B67; Wed, 22 Oct 2025 16:01:05 +0800 (CST) Received: from [10.174.179.155] (10.174.179.155) by kwepemj200013.china.huawei.com (7.202.194.25) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 22 Oct 2025 16:01:04 +0800 Message-ID: Date: Wed, 22 Oct 2025 16:01:04 +0800 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: =?UTF-8?B?TW96aWxsYSBUaHVuZGVyYmlyZCDmtYvor5XniYg=?= Subject: Re: [PATCH 5.10.y] dm: fix NULL pointer dereference in __dm_suspend() To: Sasha Levin , CC: Zheng Qixing , Mikulas Patocka , , yangerkun , "zhangyi (F)" , Hou Tao References: <2025101316-favored-pulsate-a811@gregkh> <20251014030334.3868139-1-sashal@kernel.org> From: Li Lingfeng In-Reply-To: <20251014030334.3868139-1-sashal@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To kwepemj200013.china.huawei.com (7.202.194.25) Hi, 在 2025/10/14 11:03, Sasha Levin 写道: > From: Zheng Qixing > > [ Upstream commit 8d33a030c566e1f105cd5bf27f37940b6367f3be ] > > There is a race condition between dm device suspend and table load that > can lead to null pointer dereference. The issue occurs when suspend is > invoked before table load completes: > > BUG: kernel NULL pointer dereference, address: 0000000000000054 > Oops: 0000 [#1] PREEMPT SMP PTI > CPU: 6 PID: 6798 Comm: dmsetup Not tainted 6.6.0-g7e52f5f0ca9b #62 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 > RIP: 0010:blk_mq_wait_quiesce_done+0x0/0x50 > Call Trace: > > blk_mq_quiesce_queue+0x2c/0x50 > dm_stop_queue+0xd/0x20 > __dm_suspend+0x130/0x330 > dm_suspend+0x11a/0x180 > dev_suspend+0x27e/0x560 > ctl_ioctl+0x4cf/0x850 > dm_ctl_ioctl+0xd/0x20 > vfs_ioctl+0x1d/0x50 > __se_sys_ioctl+0x9b/0xc0 > __x64_sys_ioctl+0x19/0x30 > x64_sys_call+0x2c4a/0x4620 > do_syscall_64+0x9e/0x1b0 > > The issue can be triggered as below: > > T1 T2 > dm_suspend table_load > __dm_suspend dm_setup_md_queue > dm_mq_init_request_queue > blk_mq_init_allocated_queue > => q->mq_ops = set->ops; (1) > dm_stop_queue / dm_wait_for_completion > => q->tag_set NULL pointer! (2) > => q->tag_set = set; (3) > > Fix this by checking if a valid table (map) exists before performing > request-based suspend and waiting for target I/O. When map is NULL, > skip these table-dependent suspend steps. > > Even when map is NULL, no I/O can reach any target because there is > no table loaded; I/O submitted in this state will fail early in the > DM layer. Skipping the table-dependent suspend logic in this case > is safe and avoids NULL pointer dereferences. > > Fixes: c4576aed8d85 ("dm: fix request-based dm's use of dm_wait_for_completion") > Cc: stable@vger.kernel.org > Signed-off-by: Zheng Qixing > Signed-off-by: Mikulas Patocka > [ omitted DMF_QUEUE_STOPPED flag setting and braces absent in 5.15 ] > Signed-off-by: Sasha Levin > --- > drivers/md/dm.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index 0868358a7a8d2..b51281ce15d4c 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -2457,7 +2457,7 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map, > { > bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG; > bool noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG; > - int r; > + int r = 0; > > lockdep_assert_held(&md->suspend_lock); > > @@ -2509,7 +2509,7 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map, > * Stop md->queue before flushing md->wq in case request-based > * dm defers requests to md->wq from md->queue. > */ > - if (dm_request_based(md)) > + if (map && dm_request_based(md)) > dm_stop_queue(md->queue); > It seems that before commit 80bd4a7aab4c ("blk-mq: move the srcu_struct used for quiescing to the tagset") was merged, blk_mq_wait_quiesce_done() would not attempt to access q->tag_set, so in dm_stop_queue() this kind of race condition would not cause a null pointer dereference. The change may not be necessary for 5.10, but adding it doesn’t appear to cause any issues either. > flush_workqueue(md->wq); > @@ -2519,7 +2519,8 @@ static int __dm_suspend(struct mapped_device *md, struct dm_table *map, > * We call dm_wait_for_completion to wait for all existing requests > * to finish. > */ > - r = dm_wait_for_completion(md, task_state); > + if (map) > + r = dm_wait_for_completion(md, task_state); The fix tag c4576aed8d85 ("dm: fix request-based dm's use of dm_wait_for_completion") seems to correspond to the modification of dm_wait_for_completion(). > if (!r) > set_bit(dmf_suspended_flag, &md->flags); > Perhaps adding another fix tag would be more appropriate? Thanks, Lingfeng