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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 DEF87C04AAF for ; Sat, 18 May 2019 17:49:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C0CC520873 for ; Sat, 18 May 2019 17:49:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729799AbfERRtu (ORCPT ); Sat, 18 May 2019 13:49:50 -0400 Received: from netrider.rowland.org ([192.131.102.5]:57213 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1728990AbfERRtu (ORCPT ); Sat, 18 May 2019 13:49:50 -0400 Received: (qmail 11573 invoked by uid 500); 18 May 2019 13:49:49 -0400 Received: from localhost (sendmail-bs@127.0.0.1) by localhost with SMTP; 18 May 2019 13:49:49 -0400 Date: Sat, 18 May 2019 13:49:49 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: syzbot cc: andreyknvl@google.com, , , , , , , , , , Subject: Re: KASAN: use-after-free Read in p54u_load_firmware_cb In-Reply-To: <000000000000b8203405892cee43@google.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 18 May 2019, syzbot wrote: > Hello, > > syzbot has tested the proposed patch but the reproducer still triggered > crash: > KASAN: use-after-free Read in usb_driver_release_interface > > usb 1-1: Loading firmware file isl3887usb > usb 1-1: Direct firmware load for isl3887usb failed with error -2 > usb 1-1: Firmware not found. > p54usb 1-1:0.143: failed to initialize device (-2) > ================================================================== > BUG: KASAN: use-after-free in usb_driver_release_interface+0x16b/0x190 > drivers/usb/core/driver.c:584 > Read of size 8 at addr ffff88808fc31218 by task kworker/0:1/12 Now the bad access is in a different place. That's a good sign. In this case it indicates that although udev is still hanging around, intf has already been freed. We really should acquire a reference to it instead. Alan Stern #syz test: https://github.com/google/kasan.git usb-fuzzer drivers/net/wireless/intersil/p54/p54usb.c | 43 ++++++++++++----------------- 1 file changed, 18 insertions(+), 25 deletions(-) Index: usb-devel/drivers/net/wireless/intersil/p54/p54usb.c =================================================================== --- usb-devel.orig/drivers/net/wireless/intersil/p54/p54usb.c +++ usb-devel/drivers/net/wireless/intersil/p54/p54usb.c @@ -33,6 +33,8 @@ MODULE_ALIAS("prism54usb"); MODULE_FIRMWARE("isl3886usb"); MODULE_FIRMWARE("isl3887usb"); +static struct usb_driver p54u_driver; + /* * Note: * @@ -921,9 +923,9 @@ static void p54u_load_firmware_cb(const { struct p54u_priv *priv = context; struct usb_device *udev = priv->udev; + struct usb_interface *intf = priv->intf; int err; - complete(&priv->fw_wait_load); if (firmware) { priv->fw = firmware; err = p54u_start_ops(priv); @@ -932,26 +934,22 @@ static void p54u_load_firmware_cb(const dev_err(&udev->dev, "Firmware not found.\n"); } - if (err) { - struct device *parent = priv->udev->dev.parent; - - dev_err(&udev->dev, "failed to initialize device (%d)\n", err); - - if (parent) - device_lock(parent); + complete(&priv->fw_wait_load); + /* + * At this point p54u_disconnect may have already freed + * the "priv" context. Do not use it anymore! + */ + priv = NULL; - device_release_driver(&udev->dev); - /* - * At this point p54u_disconnect has already freed - * the "priv" context. Do not use it anymore! - */ - priv = NULL; + if (err) { + dev_err(&intf->dev, "failed to initialize device (%d)\n", err); - if (parent) - device_unlock(parent); + usb_lock_device(udev); + usb_driver_release_interface(&p54u_driver, intf); + usb_unlock_device(udev); } - usb_put_dev(udev); + usb_put_intf(intf); } static int p54u_load_firmware(struct ieee80211_hw *dev, @@ -972,14 +970,14 @@ static int p54u_load_firmware(struct iee dev_info(&priv->udev->dev, "Loading firmware file %s\n", p54u_fwlist[i].fw); - usb_get_dev(udev); + usb_get_intf(intf); err = request_firmware_nowait(THIS_MODULE, 1, p54u_fwlist[i].fw, device, GFP_KERNEL, priv, p54u_load_firmware_cb); if (err) { dev_err(&priv->udev->dev, "(p54usb) cannot load firmware %s " "(%d)!\n", p54u_fwlist[i].fw, err); - usb_put_dev(udev); + usb_put_intf(intf); } return err; @@ -1011,8 +1009,6 @@ static int p54u_probe(struct usb_interfa skb_queue_head_init(&priv->rx_queue); init_usb_anchor(&priv->submitted); - usb_get_dev(udev); - /* really lazy and simple way of figuring out if we're a 3887 */ /* TODO: should just stick the identification in the device table */ i = intf->altsetting->desc.bNumEndpoints; @@ -1053,10 +1049,8 @@ static int p54u_probe(struct usb_interfa priv->upload_fw = p54u_upload_firmware_net2280; } err = p54u_load_firmware(dev, intf); - if (err) { - usb_put_dev(udev); + if (err) p54_free_common(dev); - } return err; } @@ -1072,7 +1066,6 @@ static void p54u_disconnect(struct usb_i wait_for_completion(&priv->fw_wait_load); p54_unregister_common(dev); - usb_put_dev(interface_to_usbdev(intf)); release_firmware(priv->fw); p54_free_common(dev); }