diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2015-01-27 18:16:51 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-03-18 13:22:34 +0100 |
| commit | 596c469f8f338819a95531c5bdf970b9d98e4bb9 (patch) | |
| tree | d5b543594cacc95a75abc0bdb9ead935f53306fd | |
| parent | 6e6493c26e176987bf215625ebcaea5954a05fa1 (diff) | |
| download | lwn-596c469f8f338819a95531c5bdf970b9d98e4bb9.tar.gz lwn-596c469f8f338819a95531c5bdf970b9d98e4bb9.zip | |
staging: comedi: comedi_compat32.c: fix COMEDI_CMD copy back
commit 42b8ce6f55facfa101462e694d33fc6bca471138 upstream.
`do_cmd_ioctl()` in "comedi_fops.c" handles the `COMEDI_CMD` ioctl.
This returns `-EAGAIN` if it has copied a modified `struct comedi_cmd`
back to user-space. (This occurs when the low-level Comedi driver's
`do_cmdtest()` handler returns non-zero to indicate a problem with the
contents of the `struct comedi_cmd`, or when the `struct comedi_cmd` has
the `CMDF_BOGUS` flag set.)
`compat_cmd()` in "comedi_compat32.c" handles the 32-bit compatible
version of the `COMEDI_CMD` ioctl. Currently, it never copies a 32-bit
compatible version of `struct comedi_cmd` back to user-space, which is
at odds with the way the regular `COMEDI_CMD` ioctl is handled. To fix
it, change `compat_cmd()` to copy a 32-bit compatible version of the
`struct comedi_cmd` back to user-space when the main ioctl handler
returns `-EAGAIN`.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/comedi/comedi_compat32.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/staging/comedi/comedi_compat32.c b/drivers/staging/comedi/comedi_compat32.c index ad208cdd53d4..83bcf968ac63 100644 --- a/drivers/staging/comedi/comedi_compat32.c +++ b/drivers/staging/comedi/comedi_compat32.c @@ -270,7 +270,7 @@ static int compat_cmd(struct file *file, unsigned long arg) { struct comedi_cmd __user *cmd; struct comedi32_cmd_struct __user *cmd32; - int rc; + int rc, err; cmd32 = compat_ptr(arg); cmd = compat_alloc_user_space(sizeof(*cmd)); @@ -279,7 +279,15 @@ static int compat_cmd(struct file *file, unsigned long arg) if (rc) return rc; - return translated_ioctl(file, COMEDI_CMD, (unsigned long)cmd); + rc = translated_ioctl(file, COMEDI_CMD, (unsigned long)cmd); + if (rc == -EAGAIN) { + /* Special case: copy cmd back to user. */ + err = put_compat_cmd(cmd32, cmd); + if (err) + rc = err; + } + + return rc; } /* Handle 32-bit COMEDI_CMDTEST ioctl. */ |