From nobody Sun Oct 5 20:02:15 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (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 14AAD156CA; Wed, 30 Jul 2025 07:40:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753861226; cv=none; b=RgQNwkk3Uwb8fvOiI0RKrfjcBBDnOJ39Kn3clZU7+KhnyuwhUVn2KxT8tQ36suxOksK7UDaq4jUxDI+FJ2d8Ie3OvoIwQDpvL0xfY4IImxieszmPYx6NaUgKK7pshbW5eBa/VJFA/bcItRERFicSgmKRy/kjfifH8W0ZKTurgr0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753861226; c=relaxed/simple; bh=BTXi/F3yyZKriEG4vjo4oa52GNvOBnc3dZaZErGy21o=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=iQi+JyJWFVbKallnB/sy3FQHPoOSxJgr7nG9aI0eqYaUPcmM/fbw1/KOw1+MzrACyR82m4yHCRtFNptjtD2t0PHIbdobuJk8Z5ML2f4kMfm05YHLeZ5incKwGCHQGEvwCpjQUSs8FNL4C08JuyyjVgsRm269aUd0dHnVQG+Y3+c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4bsPJJ186GzKHMWJ; Wed, 30 Jul 2025 15:40:16 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 0C5B41A0F86; Wed, 30 Jul 2025 15:40:15 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgB3QBFazIlodfjhBw--.53526S4; Wed, 30 Jul 2025 15:40:12 +0800 (CST) From: Yu Kuai To: contact@arnaud-lcm.com, hdanton@sina.com, song@kernel.org, yukuai3@huawei.com, xni@redhat.com Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH] md: fix create on open mddev lifetime regression Date: Wed, 30 Jul 2025 15:33:21 +0800 Message-Id: <20250730073321.2583158-1-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 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-CM-TRANSID: gCh0CgB3QBFazIlodfjhBw--.53526S4 X-Coremail-Antispam: 1UD129KBjvJXoW7CrW7Wry5tr4UAr4DCFWfKrg_yoW8Kr18pa yrJFs0yryUtFyfJ3yUt34DuFyrXwna9FZ2grW7Gwn8ua4fCw4UWw4S9r4qgr1DGayrJFs0 v3Wjv3WkZFy0grUanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9Y14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x 0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2 zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF 4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWU CwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCT nIWIevJa73UjIFyTuYvjfUonmRUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai Commit 9e59d609763f ("md: call del_gendisk in control path") move setting MD_DELETED from __mddev_put() to do_md_stop(), however, for the case create on open, mddev can be freed without do_md_stop(): 1) open md_probe md_alloc_and_put md_alloc mddev_alloc atomic_set(&mddev->active, 1); mddev->hold_active =3D UNTIL_IOCTL mddev_put atomic_dec_and_test(&mddev->active) if (mddev->hold_active) -> active is 0, hold_active is set md_open mddev_get atomic_inc(&mddev->active); 2) ioctl that is not STOP_ARRAY, for example, GET_ARRAY_INFO: md_ioctl mddev->hold_active =3D 0 3) close md_release mddev_put(mddev); atomic_dec_and_lock(&mddev->active, &all_mddevs_lock) __mddev_put -> hold_active is cleared, mddev will be freed queue_work(md_misc_wq, &mddev->del_work) Now that MD_DELETED is not set, before mddev is freed by mddev_delayed_delete(), md_open can still succeed and break mddev lifetime, causing mddev->kobj refcount underflow or mddev uaf problem. Fix this problem by setting MD_DELETED before queuing del_work. Reported-by: syzbot+9921e319bd6168140b40@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68894408.a00a0220.26d0e1.0012.GAE@googl= e.com/ Reported-by: syzbot+fa3a12519f0d3fd4ec16@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68894408.a00a0220.26d0e1.0013.GAE@googl= e.com/ Fixes: 9e59d609763f ("md: call del_gendisk in control path") Signed-off-by: Yu Kuai Reviewed-by: Paul Menzel Reviewed-by: Xiao Ni --- drivers/md/md.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 046fe85c76fe..5289dcc3a6af 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -636,6 +636,12 @@ static void __mddev_put(struct mddev *mddev) mddev->ctime || mddev->hold_active) return; =20 + /* + * If array is freed by stopping array, MD_DELETED is set by + * do_md_stop(), MD_DELETED is still set here in cause mddev is freed + * directly by closing a mddev that is created by create_on_open. + */ + set_bit(MD_DELETED, &mddev->flags); /* * Call queue_work inside the spinlock so that flush_workqueue() after * mddev_find will succeed in waiting for the work to be done. --=20 2.39.2