Staging: comedi: fix bug with invalid minor number usage.

Return error instead of segfaulting if user trys to run comedi_config on
a device file with and invalid minor number.

From: Frank Mori Hess <fmhess@users.sourceforge.net>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: David Schleef <ds@schleef.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index 1464f55..fbd3d1c 100644 (file)
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -104,9 +104,13 @@ static int comedi_ioctl(struct inode *inode, struct file *file,
        const unsigned minor = iminor(file->f_dentry->d_inode);
        struct comedi_device_file_info *dev_file_info =
            comedi_get_device_file_info(minor);
-       comedi_device *dev = dev_file_info->device;
+       comedi_device *dev;
        int rc;
 
+       if (dev_file_info == NULL || dev_file_info->device == NULL)
+               return -ENODEV;
+       dev = dev_file_info->device;
+
        mutex_lock(&dev->mutex);
 
        /* Device config is special, because it must work on