USB: adutux: fix NULL-derefs on disconnect

The driver was using its struct usb_device pointer as an inverted
disconnected flag, but was setting it to NULL before making sure all
completion handlers had run. This could lead to a NULL-pointer
dereference in a number of dev_dbg statements in the completion handlers
which relies on said pointer.

The pointer was also dereferenced unconditionally in a dev_dbg statement
release() something which would lead to a NULL-deref whenever a device
was disconnected before the final character-device close if debugging
was enabled.

Fix this by unconditionally stopping all I/O and preventing
resubmissions by poisoning the interrupt URBs at disconnect and using a
dedicated disconnected flag.

This also makes sure that all I/O has completed by the time the
disconnect callback returns.

Fixes: 1ef37c6047fe ("USB: adutux: remove custom debug macro and module parameter")
Fixes: 66d4bc30d128 ("USB: adutux: remove custom debug macro")
Cc: stable <stable@vger.kernel.org>     # 3.12
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20190925092913.8608-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/misc/adutux.c b/drivers/usb/misc/adutux.c
index bcc138990e2f46c2510c57c82302f46ba5d8de2b..f9efec7193590a7e41643ec4b0d827d2d11674b7 100644 (file)
--- a/drivers/usb/misc/adutux.c
+++ b/drivers/usb/misc/adutux.c
@@ -75,6 +75,7 @@ struct adu_device {
        char                    serial_number[8];
 
        int                     open_count; /* number of times this port has been opened */
+       unsigned long           disconnected:1;
 
        char            *read_buffer_primary;
        int                     read_buffer_length;
@@ -116,7 +117,7 @@ static void adu_abort_transfers(struct adu_device *dev)
 {
        unsigned long flags;
 
-       if (dev->udev == NULL)
+       if (dev->disconnected)
                return;
 
        /* shutdown transfer */
@@ -243,7 +244,7 @@ static int adu_open(struct inode *inode, struct file *file)
        }
 
        dev = usb_get_intfdata(interface);
-       if (!dev || !dev->udev) {
+       if (!dev) {
                retval = -ENODEV;
                goto exit_no_device;
        }
@@ -326,7 +327,7 @@ static int adu_release(struct inode *inode, struct file *file)
        }
 
        adu_release_internal(dev);
-       if (dev->udev == NULL) {
+       if (dev->disconnected) {
                /* the device was unplugged before the file was released */
                if (!dev->open_count)   /* ... and we're the last user */
                        adu_delete(dev);
@@ -354,7 +355,7 @@ static ssize_t adu_read(struct file *file, __user char *buffer, size_t count,
                return -ERESTARTSYS;
 
        /* verify that the device wasn't unplugged */
-       if (dev->udev == NULL) {
+       if (dev->disconnected) {
                retval = -ENODEV;
                pr_err("No device or device unplugged %d\n", retval);
                goto exit;
@@ -518,7 +519,7 @@ static ssize_t adu_write(struct file *file, const __user char *buffer,
                goto exit_nolock;
 
        /* verify that the device wasn't unplugged */
-       if (dev->udev == NULL) {
+       if (dev->disconnected) {
                retval = -ENODEV;
                pr_err("No device or device unplugged %d\n", retval);
                goto exit;
@@ -764,11 +765,14 @@ static void adu_disconnect(struct usb_interface *interface)
 
        usb_deregister_dev(interface, &adu_class);
 
+       usb_poison_urb(dev->interrupt_in_urb);
+       usb_poison_urb(dev->interrupt_out_urb);
+
        mutex_lock(&adutux_mutex);
        usb_set_intfdata(interface, NULL);
 
        mutex_lock(&dev->mtx);  /* not interruptible */
-       dev->udev = NULL;       /* poison */
+       dev->disconnected = 1;
        mutex_unlock(&dev->mtx);
 
        /* if the device is not opened, then we clean up right now */