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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D022C74A5B for ; Fri, 17 Mar 2023 10:10:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229967AbjCQKKH (ORCPT ); Fri, 17 Mar 2023 06:10:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44068 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229832AbjCQKKF (ORCPT ); Fri, 17 Mar 2023 06:10:05 -0400 Received: from m12.mail.163.com (m12.mail.163.com [220.181.12.214]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id EB2A37617D; Fri, 17 Mar 2023 03:10:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=l0+rc XAx9sjzsHZaRBR/f5UUh1q1PCzp0gO21Al0KDQ=; b=HiUf+8STawQQEKzZkTu1t MTBzM9liXFBymei0yOAA81kVC5TCd4Mwgenyb45mp9NrCZrvYzW9xEweAO5uq0oy 4EgeI9i+Pqn069gRGjRJ0KEXrJKOfCsTKxIWD9o7XCdTr9vK2g4PFFFSy/OkIPTo oubgC2TflD0m/23Vb9Fk84= Received: from leanderwang-LC2.localdomain (unknown [111.206.145.21]) by zwqz-smtp-mta-g4-1 (Coremail) with SMTP id _____wCn4kBzPBRk4VRZAQ--.53619S2; Fri, 17 Mar 2023 18:09:55 +0800 (CST) From: Zheng Wang To: valentina.manea.m@gmail.com Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, hackerzheng666@gmail.com, 1395428693sheep@gmail.com, alex000young@gmail.com, skhan@linuxfoundation.org, Zheng Wang Subject: [PATCH v3] usbip: vudc: Fix use after free bug in vudc_remove due to race condition Date: Fri, 17 Mar 2023 18:09:54 +0800 Message-Id: <20230317100954.2626573-1-zyytlz.wz@163.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID: _____wCn4kBzPBRk4VRZAQ--.53619S2 X-Coremail-Antispam: 1Uf129KBjvJXoW7tr15Ww17urWkZrW5Cr1kAFb_yoW8ZrW3pF s5WFWxCr1UJFs2vr1xtws0vF1rJanxJryUuFyxK393Zr43A34UXFyDtr1FkFWxAF9rXr4a qr4kXw1ruFyvq3DanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x0ziOB_8UUUUU= X-Originating-IP: [111.206.145.21] X-CM-SenderInfo: h2113zf2oz6qqrwthudrp/1tbiQhY1U1aEEsmuWwAAsO Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org In vudc_probe, it calls init_vudc_hw, which bound &udc->timer with v_timer. When it calls usbip_sockfd_store, it will call v_start_timer to start the timer work. When we call vudc_remove to remove the driver, theremay be a sequence as follows: Fix it by shutdown the timer work before cleanup in vudc_remove. Note that removing a driver is a root-only operation, and should never happen. But the attacker can directly unplug the usb to trigger the remove function. CPU0 CPU1 |v_timer vudc_remove | kfree(udc); | //free shost | |udc->gadget |//use The udc might be removed before v_timer finished, and UAF happens. This bug was found by Codeql static analysis and might by false positive. Fixes: b6a0ca111867 ("usbip: vudc: Add UDC specific ops") Signed-off-by: Zheng Wang --- v3: - fix the issue by adding del_timer_sync in v_stop_timer and invoke it in vudc_remove v2: - add more details about how the bug was found suggested by Shuah --- drivers/usb/usbip/vudc_dev.c | 1 + drivers/usb/usbip/vudc_transfer.c | 2 ++ 2 files changed, 3 insertions(+) diff --git a/drivers/usb/usbip/vudc_dev.c b/drivers/usb/usbip/vudc_dev.c index 2bc428f2e261..dcbfed30806d 100644 --- a/drivers/usb/usbip/vudc_dev.c +++ b/drivers/usb/usbip/vudc_dev.c @@ -633,6 +633,7 @@ int vudc_remove(struct platform_device *pdev) { struct vudc *udc = platform_get_drvdata(pdev); + v_stop_timer(udc); usb_del_gadget_udc(&udc->gadget); cleanup_vudc_hw(udc); kfree(udc); diff --git a/drivers/usb/usbip/vudc_transfer.c b/drivers/usb/usbip/vudc_transfer.c index 7e801fee33bf..562ea7b6ea2e 100644 --- a/drivers/usb/usbip/vudc_transfer.c +++ b/drivers/usb/usbip/vudc_transfer.c @@ -492,5 +492,7 @@ void v_stop_timer(struct vudc *udc) /* timer itself will take care of stopping */ dev_dbg(&udc->pdev->dev, "timer stop"); + + del_timer_sync(&t->timer); t->state = VUDC_TR_STOPPED; } -- 2.25.1