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[79.208.150.46]) by smtp.gmail.com with ESMTPSA id u11sm4067405wrn.1.2019.05.18.13.11.26 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sat, 18 May 2019 13:11:27 -0700 (PDT) Received: from localhost.daheim ([127.0.0.1] helo=debian64.localnet) by debian64.daheim with esmtp (Exim 4.92) (envelope-from ) id 1hS5fy-00024r-Df; Sat, 18 May 2019 22:11:26 +0200 From: Christian Lamparter To: Alan Stern Cc: syzbot , andreyknvl@google.com, chunkeey@googlemail.com, davem@davemloft.net, kvalo@codeaurora.org, linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, oneukum@suse.com, syzkaller-bugs@googlegroups.com Subject: Re: KASAN: use-after-free Read in p54u_load_firmware_cb Date: Sat, 18 May 2019 22:11:26 +0200 Message-ID: <1715066.X1OYgGOCOL@debian64> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org Hello, On Saturday, May 18, 2019 7:49:49 PM CEST you wrote: > On Sat, 18 May 2019, syzbot wrote: > > > > 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 Thanks. I can confirm that it works with the real ISL3887 hardware as well. Can you please spin up a patch or how should this be continued? Cheers, Christian > 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); > } > >