From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCFB2C43462 for ; Mon, 12 Apr 2021 08:42:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AFFE460241 for ; Mon, 12 Apr 2021 08:42:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237415AbhDLIm7 (ORCPT ); Mon, 12 Apr 2021 04:42:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:34264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237412AbhDLIm5 (ORCPT ); Mon, 12 Apr 2021 04:42:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 63A54611F0; Mon, 12 Apr 2021 08:42:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1618216958; bh=GapSnziyoNykp8bsRduBgImD1eNCZhBiqHYLL5VvxQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gqm9W0fCvrE5dIFli7oqz5NDbldu+OWAkYoNqfcfGzRmbxbIXVz1QBWSIC8N346j1 5dsLXjIDiK0n1A5VmdMvPdbBdddBgqcUJULN2OLFbqmN02L/Q26N5IkbQfNGIn+ZS9 9IOYOUOc1LaTqPdmQ2yuu8gLjcjq+mcof+/01684= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com, Anirudh Rayabharam , "David S. Miller" Subject: [PATCH 4.19 18/66] net: hso: fix null-ptr-deref during tty device unregistration Date: Mon, 12 Apr 2021 10:40:24 +0200 Message-Id: <20210412083958.723261908@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210412083958.129944265@linuxfoundation.org> References: <20210412083958.129944265@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Anirudh Rayabharam commit 8a12f8836145ffe37e9c8733dce18c22fb668b66 upstream. Multiple ttys try to claim the same the minor number causing a double unregistration of the same device. The first unregistration succeeds but the next one results in a null-ptr-deref. The get_free_serial_index() function returns an available minor number but doesn't assign it immediately. The assignment is done by the caller later. But before this assignment, calls to get_free_serial_index() would return the same minor number. Fix this by modifying get_free_serial_index to assign the minor number immediately after one is found to be and rename it to obtain_minor() to better reflect what it does. Similary, rename set_serial_by_index() to release_minor() and modify it to free up the minor number of the given hso_serial. Every obtain_minor() should have corresponding release_minor() call. Fixes: 72dc1c096c705 ("HSO: add option hso driver") Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com Reviewed-by: Greg Kroah-Hartman Signed-off-by: Anirudh Rayabharam Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/hso.c | 33 ++++++++++++--------------------- 1 file changed, 12 insertions(+), 21 deletions(-) --- a/drivers/net/usb/hso.c +++ b/drivers/net/usb/hso.c @@ -625,7 +625,7 @@ static struct hso_serial *get_serial_by_ return serial; } -static int get_free_serial_index(void) +static int obtain_minor(struct hso_serial *serial) { int index; unsigned long flags; @@ -633,8 +633,10 @@ static int get_free_serial_index(void) spin_lock_irqsave(&serial_table_lock, flags); for (index = 0; index < HSO_SERIAL_TTY_MINORS; index++) { if (serial_table[index] == NULL) { + serial_table[index] = serial->parent; + serial->minor = index; spin_unlock_irqrestore(&serial_table_lock, flags); - return index; + return 0; } } spin_unlock_irqrestore(&serial_table_lock, flags); @@ -643,15 +645,12 @@ static int get_free_serial_index(void) return -1; } -static void set_serial_by_index(unsigned index, struct hso_serial *serial) +static void release_minor(struct hso_serial *serial) { unsigned long flags; spin_lock_irqsave(&serial_table_lock, flags); - if (serial) - serial_table[index] = serial->parent; - else - serial_table[index] = NULL; + serial_table[serial->minor] = NULL; spin_unlock_irqrestore(&serial_table_lock, flags); } @@ -2244,6 +2243,7 @@ static int hso_stop_serial_device(struct static void hso_serial_tty_unregister(struct hso_serial *serial) { tty_unregister_device(tty_drv, serial->minor); + release_minor(serial); } static void hso_serial_common_free(struct hso_serial *serial) @@ -2267,24 +2267,22 @@ static void hso_serial_common_free(struc static int hso_serial_common_create(struct hso_serial *serial, int num_urbs, int rx_size, int tx_size) { - int minor; int i; tty_port_init(&serial->port); - minor = get_free_serial_index(); - if (minor < 0) + if (obtain_minor(serial)) goto exit2; /* register our minor number */ serial->parent->dev = tty_port_register_device_attr(&serial->port, - tty_drv, minor, &serial->parent->interface->dev, + tty_drv, serial->minor, &serial->parent->interface->dev, serial->parent, hso_serial_dev_groups); - if (IS_ERR(serial->parent->dev)) + if (IS_ERR(serial->parent->dev)) { + release_minor(serial); goto exit2; + } - /* fill in specific data for later use */ - serial->minor = minor; serial->magic = HSO_SERIAL_MAGIC; spin_lock_init(&serial->serial_lock); serial->num_rx_urbs = num_urbs; @@ -2677,9 +2675,6 @@ static struct hso_device *hso_create_bul serial->write_data = hso_std_serial_write_data; - /* and record this serial */ - set_serial_by_index(serial->minor, serial); - /* setup the proc dirs and files if needed */ hso_log_port(hso_dev); @@ -2736,9 +2731,6 @@ struct hso_device *hso_create_mux_serial serial->shared_int->ref_count++; mutex_unlock(&serial->shared_int->shared_int_lock); - /* and record this serial */ - set_serial_by_index(serial->minor, serial); - /* setup the proc dirs and files if needed */ hso_log_port(hso_dev); @@ -3123,7 +3115,6 @@ static void hso_free_interface(struct us cancel_work_sync(&serial_table[i]->async_get_intf); hso_serial_tty_unregister(serial); kref_put(&serial_table[i]->ref, hso_serial_ref_free); - set_serial_by_index(i, NULL); } }