staging: comedi: addi_apci_1564: check INSN_CONFIG_DIGITAL_TRIG shift
commit926234f1b8
upstream. 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:1e15687ea4
("staging: comedi: addi_apci_1564: add Change-of-State interrupt subdevice and required functions") Cc: <stable@vger.kernel.org> #3.17+ Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://lore.kernel.org/r/20200717145257.112660-4-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -331,14 +331,22 @@ static int apci1564_cos_insn_config(struct comedi_device *dev,
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unsigned int *data)
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{
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struct apci1564_private *devpriv = dev->private;
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unsigned int shift, oldmask;
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unsigned int shift, oldmask, himask, lomask;
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switch (data[0]) {
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case INSN_CONFIG_DIGITAL_TRIG:
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if (data[1] != 0)
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return -EINVAL;
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shift = data[3];
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oldmask = (1U << shift) - 1;
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if (shift < 32) {
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oldmask = (1U << shift) - 1;
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himask = data[4] << shift;
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lomask = data[5] << shift;
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} else {
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oldmask = 0xffffffffu;
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himask = 0;
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lomask = 0;
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}
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switch (data[2]) {
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case COMEDI_DIGITAL_TRIG_DISABLE:
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devpriv->ctrl = 0;
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@ -362,8 +370,8 @@ static int apci1564_cos_insn_config(struct comedi_device *dev,
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devpriv->mode2 &= oldmask;
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}
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/* configure specified channels */
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devpriv->mode1 |= data[4] << shift;
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devpriv->mode2 |= data[5] << shift;
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devpriv->mode1 |= himask;
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devpriv->mode2 |= lomask;
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break;
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case COMEDI_DIGITAL_TRIG_ENABLE_LEVELS:
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if (devpriv->ctrl != (APCI1564_DI_IRQ_ENA |
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@ -380,8 +388,8 @@ static int apci1564_cos_insn_config(struct comedi_device *dev,
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devpriv->mode2 &= oldmask;
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}
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/* configure specified channels */
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devpriv->mode1 |= data[4] << shift;
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devpriv->mode2 |= data[5] << shift;
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devpriv->mode1 |= himask;
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devpriv->mode2 |= lomask;
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break;
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default:
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return -EINVAL;
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