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,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 1EF28C433E0 for ; Mon, 11 Jan 2021 13:27:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D37DF21919 for ; Mon, 11 Jan 2021 13:27:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732458AbhAKNQj (ORCPT ); Mon, 11 Jan 2021 08:16:39 -0500 Received: from mail.kernel.org ([198.145.29.99]:33156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732259AbhAKNQS (ORCPT ); Mon, 11 Jan 2021 08:16:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 292932250F; Mon, 11 Jan 2021 13:16:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610370962; bh=21qRYd2b+8okBkZXWE2wqYNIaDZjh9WGDNgVvY8EEOU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LS2XbW0mIHR7XlgTQad/X/r80hE/sNPBfIfgI6pAqKiHs7RvvkK1XW8+sABfdXFG+ yFXTg0GBvQoiV9vSC3hUpTTtT6blXrXgX+5HYjBtgJoMXH0iMt5VV3gwA2Jv0LnrMc fp0UCTJ3zYBDQ0B0z0bVZs08YlQkFDajI1AWgc4c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Tetsuo Handa Subject: [PATCH 5.10 080/145] USB: cdc-wdm: Fix use after free in service_outstanding_interrupt(). Date: Mon, 11 Jan 2021 14:01:44 +0100 Message-Id: <20210111130052.372087513@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210111130048.499958175@linuxfoundation.org> References: <20210111130048.499958175@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: linux-kernel@vger.kernel.org From: Tetsuo Handa commit 5e5ff0b4b6bcb4d17b7a26ec8bcfc7dd4651684f upstream. syzbot is reporting UAF at usb_submit_urb() [1], for service_outstanding_interrupt() is not checking WDM_DISCONNECTING before calling usb_submit_urb(). Close the race by doing same checks wdm_read() does upon retry. Also, while wdm_read() checks WDM_DISCONNECTING with desc->rlock held, service_interrupt_work() does not hold desc->rlock. Thus, it is possible that usb_submit_urb() is called from service_outstanding_interrupt() from service_interrupt_work() after WDM_DISCONNECTING was set and kill_urbs() from wdm_disconnect() completed. Thus, move kill_urbs() in wdm_disconnect() to after cancel_work_sync() (which makes sure that service_interrupt_work() is no longer running) completed. Although it seems to be safe to dereference desc->intf->dev in service_outstanding_interrupt() even if WDM_DISCONNECTING was already set because desc->rlock or cancel_work_sync() prevents wdm_disconnect() from reaching list_del() before service_outstanding_interrupt() completes, let's not emit error message if WDM_DISCONNECTING is set by wdm_disconnect() while usb_submit_urb() is in progress. [1] https://syzkaller.appspot.com/bug?extid=9e04e2df4a32fb661daf Reported-by: syzbot Signed-off-by: Tetsuo Handa Cc: stable Link: https://lore.kernel.org/r/620e2ee0-b9a3-dbda-a25b-a93e0ed03ec5@i-love.sakura.ne.jp Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-wdm.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -465,13 +465,23 @@ static int service_outstanding_interrupt if (!desc->resp_count || !--desc->resp_count) goto out; + if (test_bit(WDM_DISCONNECTING, &desc->flags)) { + rv = -ENODEV; + goto out; + } + if (test_bit(WDM_RESETTING, &desc->flags)) { + rv = -EIO; + goto out; + } + set_bit(WDM_RESPONDING, &desc->flags); spin_unlock_irq(&desc->iuspin); rv = usb_submit_urb(desc->response, GFP_KERNEL); spin_lock_irq(&desc->iuspin); if (rv) { - dev_err(&desc->intf->dev, - "usb_submit_urb failed with result %d\n", rv); + if (!test_bit(WDM_DISCONNECTING, &desc->flags)) + dev_err(&desc->intf->dev, + "usb_submit_urb failed with result %d\n", rv); /* make sure the next notification trigger a submit */ clear_bit(WDM_RESPONDING, &desc->flags); @@ -1027,9 +1037,9 @@ static void wdm_disconnect(struct usb_in wake_up_all(&desc->wait); mutex_lock(&desc->rlock); mutex_lock(&desc->wlock); - kill_urbs(desc); cancel_work_sync(&desc->rxwork); cancel_work_sync(&desc->service_outs_intr); + kill_urbs(desc); mutex_unlock(&desc->wlock); mutex_unlock(&desc->rlock);