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staging: comedi: fix sparse warning in do_devconfig_ioctl() 

For the COMEDI_DEVCONFIG ioctl, the user application may embed a pointer
to firmware data within a designated element (or two elements for 64-bit
pointers) of the `options[]` array in the `struct comedi_devconfig`.
`do_devconfig_ioctl()` calls `comedi_aux_data()` to extract the pointer
value.  It needs to be treated as a `__user` pointer so the firmware
data can be copied into kernel memory, so cast the result of
`comedi_aux_data()` to avoid a "sparse" warning.  This is not ideal but
`comedi_aux_data()` is called elsewhere in a wholly kernel memory
context so we can't just change its return type to include the `__user`
tag.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2012-09-18 19:46:57 +01:00 committed by Greg Kroah-Hartman
parent 0352b932be
commit dc881f294e
1 changed files with 2 additions and 1 deletions
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3
drivers/staging/comedi/comedi_fops.c
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@ -370,7 +370,8 @@ static int do_devconfig_ioctl(struct comedi_device *dev,
return -ENOMEM;
if (copy_from_user(aux_data,
comedi_aux_data(it.options, 0), aux_len)) {
(unsigned char __user *
)comedi_aux_data(it.options, 0), aux_len)) {
vfree(aux_data);
return -EFAULT;
}