From: Ian Abbott <abbotti@xxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
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@xxxxxxxxx>
Reviewed-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
drivers/staging/comedi/comedi_compat32.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/comedi/comedi_compat32.c b/drivers/staging/comedi/comedi_compat32.c
index 2dfb06aedb15..b1c264e3a7b4 100644
--- a/drivers/staging/comedi/comedi_compat32.c
+++ b/drivers/staging/comedi/comedi_compat32.c
@@ -265,7 +265,7 @@ 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));
@@ -274,7 +274,15 @@ 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. */
--
2.3.0
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