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Staging: comedi: For COMEDI_BUFINFO, check access to command 

Don't allow COMEDI_BUFINFO ioctl if some other file object has locked
the subdevice or has an active command.  If there is no active command,
just report back the last buffer position.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Ian Abbott 2010-05-19 18:09:50 +01:00 committed by Greg Kroah-Hartman
parent 4772c018e3
commit 53fa827e29
1 changed files with 16 additions and 3 deletions
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19
drivers/staging/comedi/comedi_fops.c
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@ -83,7 +83,7 @@ static int do_subdinfo_ioctl(struct comedi_device *dev,
static int do_chaninfo_ioctl(struct comedi_device *dev,
struct comedi_chaninfo __user *arg);
static int do_bufinfo_ioctl(struct comedi_device *dev,
struct comedi_bufinfo __user *arg);
struct comedi_bufinfo __user *arg, void *file);
static int do_cmd_ioctl(struct comedi_device *dev,
struct comedi_cmd __user *arg, void *file);
static int do_lock_ioctl(struct comedi_device *dev, unsigned int arg,
@ -169,7 +169,8 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
break;
case COMEDI_BUFINFO:
rc = do_bufinfo_ioctl(dev,
(struct comedi_bufinfo __user *)arg);
(struct comedi_bufinfo __user *)arg,
file);
break;
case COMEDI_LOCK:
rc = do_lock_ioctl(dev, arg, file);
@ -563,7 +564,7 @@ static int do_chaninfo_ioctl(struct comedi_device *dev,
*/
static int do_bufinfo_ioctl(struct comedi_device *dev,
struct comedi_bufinfo __user *arg)
struct comedi_bufinfo __user *arg, void *file)
{
struct comedi_bufinfo bi;
struct comedi_subdevice *s;
@ -576,6 +577,10 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
return -EINVAL;
s = dev->subdevices + bi.subdevice;
if (s->lock && s->lock != file)
return -EACCES;
async = s->async;
if (!async) {
@ -588,6 +593,13 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
bi.bytes_written = 0;
goto copyback;
}
if (!s->busy) {
bi.bytes_read = 0;
bi.bytes_written = 0;
goto copyback_position;
}
if (s->busy != file)
return -EACCES;
if (bi.bytes_read && (s->subdev_flags & SDF_CMD_READ)) {
bi.bytes_read = comedi_buf_read_alloc(async, bi.bytes_read);
@ -606,6 +618,7 @@ static int do_bufinfo_ioctl(struct comedi_device *dev,
comedi_buf_write_free(async, bi.bytes_written);
}
copyback_position:
bi.buf_write_count = async->buf_write_count;
bi.buf_write_ptr = async->buf_write_ptr;
bi.buf_read_count = async->buf_read_count;