From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (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 AF7E0305070 for ; Wed, 22 Oct 2025 08:21:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761121307; cv=none; b=oFexRGICTclLLG2+4xGXQNMHp45+kBIRZscCDQMRoF5789mCol5Rtv7JUUUArCPoRPbJSGYiOk58ABRH9BgTRcm22EMxFa1PYIBBUJDqFR8FkQvpeTDgjwHlOPev5vCLi5/dv+Lr9CEQEickSF0lOroTpeAys9N5vJCMSr9LI6w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761121307; c=relaxed/simple; bh=ZkLVJ4CPf+Od02T5p4UpDr1VbFhpdPQXCD2ro3NnE+Q=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=GhaeO2a1viJcDe9hw9sMOC0eAS2nilZDS6H5V2uUc73VUs6ppYP7E3vFNOWk58p5T4Cv1nPsVmv/ajg3rH3cGI8C66pRtfYWVDL3+4D3U3+BaUWNj/lRAaev64tArg2KjAD1cpMSi3Vn7dsfpuVL5yUATyhFt17f9k+Sg46UZLE= 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=PvJ7asxK; arc=none smtp.client-ip=45.249.212.188 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="PvJ7asxK" Received: from canpmsgout05.his.huawei.com (unknown [172.19.92.145]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4cs2DQ2yrCzVmdk for ; Wed, 22 Oct 2025 16:20:54 +0800 (CST) dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=27ELNbxEYhJODT7dorjM6ja6xnMNYxTKfYD+DwnBsm4=; b=PvJ7asxKUk9LiYCYVeCbhan0UIpdlA3kLQTgqcndPvDrIvp6v2L3UzxV66GcZcMrzj7mhRr6S DnyQuF1hAeGKzGEA3i+Pb2GqaQVx2SX0UvqYfuZspybbQrnjpyOWIsK5cd6q1m2coFyvCe3fs26 lvq3cQ3cxp+Lppw9X01p6/Y= Received: from mail.maildlp.com (unknown [172.19.163.174]) by canpmsgout05.his.huawei.com (SkyGuard) with ESMTPS id 4cs2DP6YHyz12Ldj; Wed, 22 Oct 2025 16:20:53 +0800 (CST) Received: from kwepemj200013.china.huawei.com (unknown [7.202.194.25]) by mail.maildlp.com (Postfix) with ESMTPS id 20C2814010D; Wed, 22 Oct 2025 16:21:35 +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 16:21:34 +0800 Message-ID: <1767bec2-b660-42b2-b828-b221e0896eba@huawei.com> Date: Wed, 22 Oct 2025 16:21:33 +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: Greg KH CC: Sasha Levin , , Zheng Qixing , Mikulas Patocka , , yangerkun , "zhangyi (F)" , Hou Tao References: <2025101316-favored-pulsate-a811@gregkh> <20251014030334.3868139-1-sashal@kernel.org> <2025102252-abrasive-glamorous-465b@gregkh> From: Li Lingfeng In-Reply-To: <2025102252-abrasive-glamorous-465b@gregkh> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200001.china.huawei.com (7.221.188.67) To kwepemj200013.china.huawei.com (7.202.194.25) Hi, 在 2025/10/22 16:10, Greg KH 写道: > On Wed, Oct 22, 2025 at 04:01:04PM +0800, Li Lingfeng wrote: >> 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? > Those tags come directly from the original commit. Thanks for the clarification. Since the patch has already been merged into the mainline tree, we can't update the commit there. I was just wondering if it would be acceptable to add an additional “Fixes” tag when applying it to the stable branch, before merging. Thanks, Lingfeng. >