comedi: Fix some signed shift left operations

commit ab705c8 upstream.

Correct some left shifts of the signed integer constant 1 by some
unsigned number less than 32.  Change the constant to 1U to avoid
shifting a 1 into the sign bit.

The corrected functions are comedi_dio_insn_config(),
comedi_dio_update_state(), and __comedi_device_postconfig().

Fixes: e523c6c ("staging: comedi: drivers: introduce comedi_dio_insn_config()")
Fixes: 05e60b1 ("staging: comedi: drivers: introduce comedi_dio_update_state()")
Fixes: 09567cb ("staging: comedi: initialize subdevice s->io_bits in postconfig")
Cc: stable@vger.kernel.org # 5.13+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250707121555.65424-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: ian-abbott

drivers/comedi/drivers.c

@@ -339,10 +339,10 @@ int comedi_dio_insn_config(struct comedi_device *dev,
 			   unsigned int *data,
 			   unsigned int mask)
 {
-	unsigned int chan_mask = 1 << CR_CHAN(insn->chanspec);
+	unsigned int chan = CR_CHAN(insn->chanspec);
 
-	if (!mask)
-		mask = chan_mask;
+	if (!mask && chan < 32)
+		mask = 1U << chan;
 
 	switch (data[0]) {
 	case INSN_CONFIG_DIO_INPUT:
@@ -382,7 +382,7 @@ EXPORT_SYMBOL_GPL(comedi_dio_insn_config);
 unsigned int comedi_dio_update_state(struct comedi_subdevice *s,
 				     unsigned int *data)
 {
-	unsigned int chanmask = (s->n_chan < 32) ? ((1 << s->n_chan) - 1)
+	unsigned int chanmask = (s->n_chan < 32) ? ((1U << s->n_chan) - 1)
 						 : 0xffffffff;
 	unsigned int mask = data[0] & chanmask;
 	unsigned int bits = data[1];
@@ -625,8 +625,8 @@ static int insn_rw_emulate_bits(struct comedi_device *dev,
 	if (insn->insn == INSN_WRITE) {
 		if (!(s->subdev_flags & SDF_WRITABLE))
 			return -EINVAL;
-		_data[0] = 1 << (chan - base_chan);		    /* mask */
-		_data[1] = data[0] ? (1 << (chan - base_chan)) : 0; /* bits */
+		_data[0] = 1U << (chan - base_chan);		     /* mask */
+		_data[1] = data[0] ? (1U << (chan - base_chan)) : 0; /* bits */
 	}
 
 	ret = s->insn_bits(dev, s, &_insn, _data);
@@ -709,7 +709,7 @@ static int __comedi_device_postconfig(struct comedi_device *dev)
 
 		if (s->type == COMEDI_SUBD_DO) {
 			if (s->n_chan < 32)
-				s->io_bits = (1 << s->n_chan) - 1;
+				s->io_bits = (1U << s->n_chan) - 1;
 			else
 				s->io_bits = 0xffffffff;
 		}