diff options
author | Ian Abbott <abbotti@mev.co.uk> | 2014-10-08 16:09:14 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-20 10:56:17 +0800 |
commit | 6cab7a37f5c048bb2a768f24b0ec748b052fda09 (patch) | |
tree | 739e8ac9cfa938de3d2e67608151f0a57b5c5d74 /drivers/staging | |
parent | f114040e3ea6e07372334ade75d1ee0775c355e1 (diff) | |
download | op-kernel-dev-6cab7a37f5c048bb2a768f24b0ec748b052fda09.zip op-kernel-dev-6cab7a37f5c048bb2a768f24b0ec748b052fda09.tar.gz |
staging: comedi: (regression) channel list must be set for COMEDI_CMD ioctl
`do_cmd_ioctl()`, the handler for the `COMEDI_CMD` ioctl can incorrectly
call the Comedi subdevice's `do_cmd()` handler with a NULL channel list
pointer. This is a regression as the `do_cmd()` handler has never been
expected to deal with that, leading to a kernel OOPS when it tries to
dereference it.
A NULL channel list pointer is allowed for the `COMEDI_CMDTEST` ioctl,
handled by `do_cmdtest_ioctl()` and the subdevice's `do_cmdtest()`
handler, but not for the `COMEDI_CMD` ioctl and its handlers.
Both `do_cmd_ioctl()` and `do_cmdtest_ioctl()` call
`__comedi_get_user_chanlist()` to copy the channel list from user memory
into dynamically allocated kernel memory and check it for consistency.
That function currently returns 0 if the `user_chanlist` parameter
(pointing to the channel list in user memory) is NULL. That's fine for
`do_cmdtest_ioctl()`, but `do_cmd_ioctl()` incorrectly assumes the
kernel copy of the channel list has been set-up correctly.
Fix it by not allowing the `user_chanlist` parameter to be NULL in
`__comedi_get_user_chanlist()`, and only calling it from
`do_cmdtest_ioctl()` if the parameter is non-NULL.
Thanks to Bernd Porr for reporting the bug via an initial patch sent
privately.
Fixes: c6cd0eefb27b ("staging: comedi: comedi_fops: introduce __comedi_get_user_chanlist()")
Reported-by: Bernd Porr <mail@berndporr.me.uk>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Bernd Porr <mail@berndporr.me.uk>
Cc: <stable@vger.kernel.org> # 3.15.y 3.16.y 3.17.y
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging')
-rw-r--r-- | drivers/staging/comedi/comedi_fops.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c index 495969f..a9b7fe5 100644 --- a/drivers/staging/comedi/comedi_fops.c +++ b/drivers/staging/comedi/comedi_fops.c @@ -1462,10 +1462,6 @@ static int __comedi_get_user_chanlist(struct comedi_device *dev, unsigned int *chanlist; int ret; - /* user_chanlist could be NULL for do_cmdtest ioctls */ - if (!user_chanlist) - return 0; - chanlist = memdup_user(user_chanlist, cmd->chanlist_len * sizeof(unsigned int)); if (IS_ERR(chanlist)) @@ -1609,10 +1605,13 @@ static int do_cmdtest_ioctl(struct comedi_device *dev, s = &dev->subdevices[cmd.subdev]; - /* load channel/gain list */ - ret = __comedi_get_user_chanlist(dev, s, user_chanlist, &cmd); - if (ret) - return ret; + /* user_chanlist can be NULL for COMEDI_CMDTEST ioctl */ + if (user_chanlist) { + /* load channel/gain list */ + ret = __comedi_get_user_chanlist(dev, s, user_chanlist, &cmd); + if (ret) + return ret; + } ret = s->do_cmdtest(dev, s, &cmd); |