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[85.224.241.81]) by smtp.gmail.com with ESMTPSA id 4sm557492ljv.87.2019.10.09.08.38.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 09 Oct 2019 08:38:53 -0700 (PDT) Received: from johan by xi.terra with local (Exim 4.92.2) (envelope-from ) id 1iIE3J-0002HB-Kq; Wed, 09 Oct 2019 17:39:01 +0200 From: Johan Hovold To: Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, Keith Packard , Juergen Stuber , Johan Hovold , stable Subject: [PATCH 5/5] USB: yurex: fix NULL-derefs on disconnect Date: Wed, 9 Oct 2019 17:38:48 +0200 Message-Id: <20191009153848.8664-6-johan@kernel.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191009153848.8664-1-johan@kernel.org> References: <20191009153848.8664-1-johan@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The driver was using its struct usb_interface pointer as an inverted disconnected flag, but was setting it to NULL without making sure all code paths that used it were done with it. Before commit ef61eb43ada6 ("USB: yurex: Fix protection fault after device removal") this included the interrupt-in completion handler, but there are further accesses in dev_err and dev_dbg statements in yurex_write() and the driver-data destructor (sic!). Fix this by unconditionally stopping also the control URB at disconnect and by using a dedicated disconnected flag. Note that we need to take a reference to the struct usb_interface to avoid a use-after-free in the destructor whenever the device was disconnected while the character device was still open. Fixes: aadd6472d904 ("USB: yurex.c: remove dbg() usage") Fixes: 45714104b9e8 ("USB: yurex.c: remove err() usage") Cc: stable # 3.5: ef61eb43ada6 Signed-off-by: Johan Hovold --- drivers/usb/misc/yurex.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c index 8d52d4336c29..be0505b8b5d4 100644 --- a/drivers/usb/misc/yurex.c +++ b/drivers/usb/misc/yurex.c @@ -60,6 +60,7 @@ struct usb_yurex { struct kref kref; struct mutex io_mutex; + unsigned long disconnected:1; struct fasync_struct *async_queue; wait_queue_head_t waitq; @@ -107,6 +108,7 @@ static void yurex_delete(struct kref *kref) dev->int_buffer, dev->urb->transfer_dma); usb_free_urb(dev->urb); } + usb_put_intf(dev->interface); usb_put_dev(dev->udev); kfree(dev); } @@ -205,7 +207,7 @@ static int yurex_probe(struct usb_interface *interface, const struct usb_device_ init_waitqueue_head(&dev->waitq); dev->udev = usb_get_dev(interface_to_usbdev(interface)); - dev->interface = interface; + dev->interface = usb_get_intf(interface); /* set up the endpoint information */ iface_desc = interface->cur_altsetting; @@ -316,8 +318,9 @@ static void yurex_disconnect(struct usb_interface *interface) /* prevent more I/O from starting */ usb_poison_urb(dev->urb); + usb_poison_urb(dev->cntl_urb); mutex_lock(&dev->io_mutex); - dev->interface = NULL; + dev->disconnected = 1; mutex_unlock(&dev->io_mutex); /* wakeup waiters */ @@ -405,7 +408,7 @@ static ssize_t yurex_read(struct file *file, char __user *buffer, size_t count, dev = file->private_data; mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* already disconnected */ + if (dev->disconnected) { /* already disconnected */ mutex_unlock(&dev->io_mutex); return -ENODEV; } @@ -440,7 +443,7 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer, goto error; mutex_lock(&dev->io_mutex); - if (!dev->interface) { /* already disconnected */ + if (dev->disconnected) { /* already disconnected */ mutex_unlock(&dev->io_mutex); retval = -ENODEV; goto error; -- 2.23.0