diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2013-01-28 16:14:31 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-30 11:47:47 +0100 |
| commit | 754ab5c0e55dd118273ca2c217c4d95e9fbc8259 (patch) | |
| tree | 9ad32259cc7428c9762b45bc75b48e1324cc3369 | |
| parent | 612588a886965706e9593626c277e561c1932249 (diff) | |
staging: comedi: disallow COMEDI_DEVCONFIG on non-board minors
Comedi has two sorts of minor devices:
(a) normal board minor devices in the range 0 to
COMEDI_NUM_BOARD_MINORS-1 inclusive; and
(b) special subdevice minor devices in the range COMEDI_NUM_BOARD_MINORS
upwards that are used to open the same underlying comedi device as the
normal board minor devices, but with non-default read and write
subdevices for asynchronous commands.
The special subdevice minor devices get created when a board supporting
asynchronous commands is attached to a normal board minor device, and
destroyed when the board is detached from the normal board minor device.
One way to attach or detach a board is by using the COMEDI_DEVCONFIG
ioctl. This should only be used on normal board minors as the special
subdevice minors are too ephemeral. In particular, the change
introduced in commit 7d3135af399e92cf4c9bbc5f86b6c140aab3b88c ("staging:
comedi: prevent auto-unconfig of manually configured devices") breaks
horribly for special subdevice minor devices.
Since there's no legitimate use for the COMEDI_DEVCONFIG ioctl on a
special subdevice minor device node, disallow it and return -ENOTTY.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index fa534fe4864b..38e4fcb418c0 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1633,6 +1633,11 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd, /* Device config is special, because it must work on * an unconfigured device. */ if (cmd == COMEDI_DEVCONFIG) { + if (minor >= COMEDI_NUM_BOARD_MINORS) { + /* Device config not appropriate on non-board minors. */ + rc = -ENOTTY; + goto done; + } rc = do_devconfig_ioctl(dev, (struct comedi_devconfig __user *)arg); if (rc == 0) |