In this conditional statement, if (chan < 16), but the instruction passed
in data[0] is INSN_CONFIG_DIO_QUERY, the function does not return early,
but the else-branch does not get executed either. As a result, mask
would be used uninitialized in the next line. We want
comedi_dio_insn_config() to use a chan_mask based on the chanspec for the
INSN_CONFIG_DIO_QUERY instruction, so mask should be initialized to 0.
Then, if instead the instruction is INSN_CONFIG_DIO_{INPUT,OUTPUT}, we
return an error if (chan < 16) as these are invalid instructions for
ports 0 and 1, or update the mask otherwise, so all the io_bits are
modified for port 2. This ensures that mask is always initialized by the
time it is used.
Signed-off-by: Chase Southwood <chase.southwood@xxxxxxxxx>
---
2: Addressed all of the comments provided by Hartley regarding correct
structure of this patch.
Hopefully everything looks better!
drivers/staging/comedi/drivers/addi_apci_3xxx.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/comedi/drivers/addi_apci_3xxx.c b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
index ceadf8e..1f3b668 100644
--- a/drivers/staging/comedi/drivers/addi_apci_3xxx.c
+++ b/drivers/staging/comedi/drivers/addi_apci_3xxx.c
@@ -680,7 +680,7 @@ static int apci3xxx_dio_insn_config(struct comedi_device *dev,
unsigned int *data)
{
unsigned int chan = CR_CHAN(insn->chanspec);
- unsigned int mask;
+ unsigned int mask = 0;
int ret;
/*
@@ -688,12 +688,13 @@ static int apci3xxx_dio_insn_config(struct comedi_device *dev,
* Port 1 (channels 8-15) are always outputs
* Port 2 (channels 16-23) are programmable i/o
*/
- if (chan < 16) {
- if (data[0] != INSN_CONFIG_DIO_QUERY)
+ if (data[0] != INSN_CONFIG_DIO_QUERY) {
+ /* ignore all other instructions for ports 0 and 1 */
+ if (chan < 16)
return -EINVAL;
- } else {
- /* changing any channel in port 2 changes the entire port */
- mask = 0xff0000;
+ else
+ /* changing any channel in port 2 changes the entire port */
+ mask = 0xff0000;
}
ret = comedi_dio_insn_config(dev, s, insn, data, mask);
--
1.8.5.3
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