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 90BC6C433EF for ; Tue, 15 Mar 2022 17:46:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350708AbiCORrb (ORCPT ); Tue, 15 Mar 2022 13:47:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238431AbiCORra (ORCPT ); Tue, 15 Mar 2022 13:47:30 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A93615004F for ; Tue, 15 Mar 2022 10:46:18 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 441606159F for ; Tue, 15 Mar 2022 17:46:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E16EBC340EE; Tue, 15 Mar 2022 17:46:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1647366377; bh=DjJSE7dgDeuK85m2onbsvMeDjbcQVRhHjt8kg7u4RnA=; h=Subject:To:From:Date:From; b=LsF4H9xvcnQoPEOy58nwTpRQ4PZuiDjT6Zn0mznXGJk5zryCqDnz8ER48yOLgNySq dOFtmnMjBbWuah0q6Mcs22yJhlocv+yNDKTSV4aCAJm6MOGC5TPcKEWVmnFaCmk8U7 4hW2AxLkaoUqoLLypNi78ocJS2vOT+uogIg5GKAY= Subject: patch "usb: gadget: Fix use-after-free bug by not setting udc->dev.driver" added to usb-linus To: stern@rowland.harvard.edu, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Tue, 15 Mar 2022 18:46:10 +0100 Message-ID: <1647366370162254@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled usb: gadget: Fix use-after-free bug by not setting udc->dev.driver to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 16b1941eac2bd499f065a6739a40ce0011a3d740 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Sat, 5 Mar 2022 21:47:22 -0500 Subject: usb: gadget: Fix use-after-free bug by not setting udc->dev.driver The syzbot fuzzer found a use-after-free bug: BUG: KASAN: use-after-free in dev_uevent+0x712/0x780 drivers/base/core.c:2320 Read of size 8 at addr ffff88802b934098 by task udevd/3689 CPU: 2 PID: 3689 Comm: udevd Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255 __kasan_report mm/kasan/report.c:442 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 dev_uevent+0x712/0x780 drivers/base/core.c:2320 uevent_show+0x1b8/0x380 drivers/base/core.c:2391 dev_attr_show+0x4b/0x90 drivers/base/core.c:2094 Although the bug manifested in the driver core, the real cause was a race with the gadget core. dev_uevent() does: if (dev->driver) add_uevent_var(env, "DRIVER=%s", dev->driver->name); and between the test and the dereference of dev->driver, the gadget core sets dev->driver to NULL. The race wouldn't occur if the gadget core registered its devices on a real bus, using the standard synchronization techniques of the driver core. However, it's not necessary to make such a large change in order to fix this bug; all we need to do is make sure that udc->dev.driver is always NULL. In fact, there is no reason for udc->dev.driver ever to be set to anything, let alone to the value it currently gets: the address of the gadget's driver. After all, a gadget driver only knows how to manage a gadget, not how to manage a UDC. This patch simply removes the statements in the gadget core that touch udc->dev.driver. Fixes: 2ccea03a8f7e ("usb: gadget: introduce UDC Class") CC: Reported-and-tested-by: syzbot+348b571beb5eeb70a582@syzkaller.appspotmail.com Signed-off-by: Alan Stern Link: https://lore.kernel.org/r/YiQgukfFFbBnwJ/9@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/udc/core.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c index 568534a0d17c..c109b069f511 100644 --- a/drivers/usb/gadget/udc/core.c +++ b/drivers/usb/gadget/udc/core.c @@ -1436,7 +1436,6 @@ static void usb_gadget_remove_driver(struct usb_udc *udc) usb_gadget_udc_stop(udc); udc->driver = NULL; - udc->dev.driver = NULL; udc->gadget->dev.driver = NULL; } @@ -1498,7 +1497,6 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri driver->function); udc->driver = driver; - udc->dev.driver = &driver->driver; udc->gadget->dev.driver = &driver->driver; usb_gadget_udc_set_speed(udc, driver->max_speed); @@ -1521,7 +1519,6 @@ static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *dri dev_err(&udc->dev, "failed to start %s: %d\n", udc->driver->function, ret); udc->driver = NULL; - udc->dev.driver = NULL; udc->gadget->dev.driver = NULL; return ret; } -- 2.35.1