From patchwork Tue Apr 6 12:43:59 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anirudh Rayabharam X-Patchwork-Id: 12185245 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,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=unavailable 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 26E94C43460 for ; Tue, 6 Apr 2021 13:01:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E26DE613CF for ; Tue, 6 Apr 2021 13:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344293AbhDFNBJ (ORCPT ); Tue, 6 Apr 2021 09:01:09 -0400 Received: from sender4-of-o53.zoho.com ([136.143.188.53]:21353 "EHLO sender4-of-o53.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344285AbhDFNBI (ORCPT ); Tue, 6 Apr 2021 09:01:08 -0400 X-Greylist: delayed 912 seconds by postgrey-1.27 at vger.kernel.org; Tue, 06 Apr 2021 09:01:08 EDT ARC-Seal: i=1; a=rsa-sha256; t=1617713124; cv=none; d=zohomail.com; s=zohoarc; b=AksbyrHmkX3dwlHkSpJIHQP+nJwA6iHXpM0kqQOvKDC5H3kduQu7WPR61wfyNizycuNcYgdA0dNVwHhA6kcB2Ppd2pUrB1ueckODfmAVb3Qo8nuG8uch4S3pCCNrtirXRirTpJAmq8XScrimHG4gwTnT+or/QdVg0AHFS6x5+/0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1617713124; h=Content-Transfer-Encoding:Cc:Date:From:MIME-Version:Message-ID:Subject:To; bh=m3YhZRYhbPszqTHrr3Ftf84/MKjbvjCe58AbZURF9HY=; b=GQeS8q01rG9jeLrfIrUhsDzav8p6T9GlTrs/tXaoXhGmXb1rpRQMA8mGFhwYpOtV5GSXE78Y9QmaaFJJyvVHSIIr5HgFVKLz3J6jrpP+agdG2LKYK1qnBEh/R6VisR/9MUDH84iMM/rBA64JWU8h4EbClyKiQhxLeh1U/Nm31Z0= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=anirudhrb.com; spf=pass smtp.mailfrom=mail@anirudhrb.com; dmarc=pass header.from= header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1617713124; s=zoho; d=anirudhrb.com; i=mail@anirudhrb.com; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Transfer-Encoding; bh=m3YhZRYhbPszqTHrr3Ftf84/MKjbvjCe58AbZURF9HY=; b=l9hF+jN+xbKTmXbM3zc70VXURx8F7QzRjsk4u3xdEB8V7g5+D8txqXea6PhS3YNa NiwHajt5InGLlEpCMiZPj+sbtE5B5tsMhU8/oNkmiwZErUp/rtAkbghd18GD4t/EDYz SxanGDN0ixZLtC7Jm8uK9AUacM9hbUuABExBTkk8= Received: from localhost.localdomain (49.207.62.127 [49.207.62.127]) by mx.zohomail.com with SMTPS id 1617713118803591.989363998497; Tue, 6 Apr 2021 05:45:18 -0700 (PDT) From: Anirudh Rayabharam To: "David S. Miller" , Jakub Kicinski , Oliver Neukum , Emil Renner Berthing , Geert Uytterhoeven , Zheng Yongjun , Rustam Kovhaev , Anirudh Rayabharam Cc: gregkh@linuxfoundation.org, syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com, linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] net: hso: fix null-ptr-deref during tty device unregistration Date: Tue, 6 Apr 2021 18:13:59 +0530 Message-Id: <20210406124402.20930-1-mail@anirudhrb.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-ZohoMailClient: External Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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. Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com Tested-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com Signed-off-by: Anirudh Rayabharam Reviewed-by: Greg Kroah-Hartman --- drivers/net/usb/hso.c | 32 ++++++++++++-------------------- 1 file changed, 12 insertions(+), 20 deletions(-) diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c index 31d51346786a..295ca330e70c 100644 --- a/drivers/net/usb/hso.c +++ b/drivers/net/usb/hso.c @@ -611,7 +611,7 @@ static struct hso_serial *get_serial_by_index(unsigned index) return serial; } -static int get_free_serial_index(void) +static int obtain_minor(struct hso_serial *serial) { int index; unsigned long flags; @@ -619,8 +619,10 @@ 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); @@ -629,15 +631,12 @@ 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); } @@ -2230,6 +2229,7 @@ static int hso_stop_serial_device(struct hso_device *hso_dev) 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) @@ -2258,19 +2258,18 @@ static int hso_serial_common_create(struct hso_serial *serial, int num_urbs, 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; @@ -2667,9 +2666,6 @@ static struct hso_device *hso_create_bulk_serial_device( 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); @@ -2726,9 +2722,6 @@ struct hso_device *hso_create_mux_serial_device(struct usb_interface *interface, 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); @@ -3113,7 +3106,6 @@ static void hso_free_interface(struct usb_interface *interface) 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); } }