From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 47D73220696; Mon, 18 Aug 2025 13:42:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524569; cv=none; b=XhLq+whYSq80J3Rv8Agq+Vdythc23KGGqXkwQoBdwk5GRGc0UBEWlbz+NiiLvEqMdEYV4WOEvqSf6yTxRw6O8ajlHFlDN/Dds63o6XPWEV4ZQpQfX+D4QfLKISUS56/hApdA81YBis2e9Qx/jVx3WWUujjT3BCAjndXq1Xu0P8k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755524569; c=relaxed/simple; bh=FmtzCpnFLxXykBtoUpNiPdqqnYGUuJrRKSBHCXOJtww=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y4TvR8V7j3DbGAREvLiJ73OCr31OAlEMQDfI12sNm7ebNTMx1HR9UMcxCtc5vb61JaJWvDNQ1TxleIPa93R4MWmoF9uWGvP/P3gvmo3MKQoNiZOWzpbrbydW4v4i3O9CbYEhOIGpIDQgwJeSz/JZeSPPZYWxGWMKphTgwfAnwZ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1oBiNo8V; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="1oBiNo8V" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BEC0CC116B1; Mon, 18 Aug 2025 13:42:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755524569; bh=FmtzCpnFLxXykBtoUpNiPdqqnYGUuJrRKSBHCXOJtww=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1oBiNo8VSdM56AeJQ4y3CGU1sFELVnzJVlmf5PV7Q6XdnSYUi8gWnO1NkdDlC2AKl D/AVA/jTpgjh5oKUPZn8xFeagMTRNIYTNUILAMvJNF3HgWZ32m9MORiWFddAGv+wEt gfTOjU7jSydLn2abXIUAm47Q+OX0/paUPqQoT4gE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+9921e319bd6168140b40@syzkaller.appspotmail.com, syzbot+fa3a12519f0d3fd4ec16@syzkaller.appspotmail.com, Yu Kuai , Paul Menzel , Xiao Ni Subject: [PATCH 6.15 513/515] md: fix create on open mddev lifetime regression Date: Mon, 18 Aug 2025 14:48:19 +0200 Message-ID: <20250818124518.185025341@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124458.334548733@linuxfoundation.org> References: <20250818124458.334548733@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yu Kuai commit 1df1fc845d221eb646539836dbf509eb96b41afd upstream. Commit 9e59d609763f ("md: call del_gendisk in control path") moves 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 = 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 = 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@google.com/ Reported-by: syzbot+fa3a12519f0d3fd4ec16@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68894408.a00a0220.26d0e1.0013.GAE@google.com/ Fixes: 9e59d609763f ("md: call del_gendisk in control path") Link: https://lore.kernel.org/linux-raid/20250730073321.2583158-1-yukuai1@huaweicloud.com Signed-off-by: Yu Kuai Reviewed-by: Paul Menzel Reviewed-by: Xiao Ni Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -614,6 +614,12 @@ static void __mddev_put(struct mddev *md return; /* + * If array is freed by stopping array, MD_DELETED is set by + * do_md_stop(), MD_DELETED is still set here in case 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. */