commit: 754ab5c0e55dd118273ca2c217c4d95e9fbc8259
From: Ian Abbott <[email protected]>
Date: Mon, 28 Jan 2013 16:14:31 +0000
Subject: 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 <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/staging/comedi/comedi_fops.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/staging/comedi/comedi_fops.c
b/drivers/staging/comedi/comedi_fops.c
index fa534fe..38e4fcb 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)
--
1.7.10.4
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