staging: comedi: comedi_compat32.c: fix COMEDI_CMD copy back
`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> Cc: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -262,7 +262,7 @@ static int compat_cmd(struct file *file, unsigned long arg)
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{
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{
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struct comedi_cmd __user *cmd;
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struct comedi_cmd __user *cmd;
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struct comedi32_cmd_struct __user *cmd32;
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struct comedi32_cmd_struct __user *cmd32;
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int rc;
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int rc, err;
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cmd32 = compat_ptr(arg);
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cmd32 = compat_ptr(arg);
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cmd = compat_alloc_user_space(sizeof(*cmd));
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cmd = compat_alloc_user_space(sizeof(*cmd));
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@ -271,7 +271,15 @@ static int compat_cmd(struct file *file, unsigned long arg)
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if (rc)
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if (rc)
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return rc;
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return rc;
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return translated_ioctl(file, COMEDI_CMD, (unsigned long)cmd);
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rc = translated_ioctl(file, COMEDI_CMD, (unsigned long)cmd);
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if (rc == -EAGAIN) {
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/* Special case: copy cmd back to user. */
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err = put_compat_cmd(cmd32, cmd);
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if (err)
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rc = err;
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}
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return rc;
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}
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}
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/* Handle 32-bit COMEDI_CMDTEST ioctl. */
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/* Handle 32-bit COMEDI_CMDTEST ioctl. */
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