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staging: comedi: addi_apci_1032: check INSN_CONFIG_DIGITAL_TRIG shift

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The `INSN_CONFIG` comedi instruction with sub-instruction code
`INSN_CONFIG_DIGITAL_TRIG` includes a base channel in `data[3]`. This is
used as a right shift amount for other bitmask values without being
checked.  Shift amounts greater than or equal to 32 will result in
undefined behavior.  Add code to deal with this.

Fixes: 33cdce6293 ("staging: comedi: addi_apci_1032: conform to new INSN_CONFIG_DIGITAL_TRIG")
Cc: <stable@vger.kernel.org> #3.8+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20200717145257.112660-3-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2020-07-17 15:52:55 +01:00 committed by Greg Kroah-Hartman
parent f07804ec77
commit 0bd0db42a0
1 changed files with 14 additions and 6 deletions
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18
drivers/staging/comedi/drivers/addi_apci_1032.c
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@ -106,14 +106,22 @@ static int apci1032_cos_insn_config(struct comedi_device *dev,
unsigned int *data)
{
struct apci1032_private *devpriv = dev->private;
unsigned int shift, oldmask;
unsigned int shift, oldmask, himask, lomask;
switch (data[0]) {
case INSN_CONFIG_DIGITAL_TRIG:
if (data[1] != 0)
return -EINVAL;
shift = data[3];
if (shift < 32) {
oldmask = (1U << shift) - 1;
himask = data[4] << shift;
lomask = data[5] << shift;
} else {
oldmask = 0xffffffffu;
himask = 0;
lomask = 0;
}
switch (data[2]) {
case COMEDI_DIGITAL_TRIG_DISABLE:
devpriv->ctrl = 0;
@ -136,8 +144,8 @@ static int apci1032_cos_insn_config(struct comedi_device *dev,
devpriv->mode2 &= oldmask;
}
/* configure specified channels */
devpriv->mode1 |= data[4] << shift;
devpriv->mode2 |= data[5] << shift;
devpriv->mode1 |= himask;
devpriv->mode2 |= lomask;
break;
case COMEDI_DIGITAL_TRIG_ENABLE_LEVELS:
if (devpriv->ctrl != (APCI1032_CTRL_INT_ENA |
@ -154,8 +162,8 @@ static int apci1032_cos_insn_config(struct comedi_device *dev,
devpriv->mode2 &= oldmask;
}
/* configure specified channels */
devpriv->mode1 |= data[4] << shift;
devpriv->mode2 |= data[5] << shift;
devpriv->mode1 |= himask;
devpriv->mode2 |= lomask;
break;
default:
return -EINVAL;