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Commit 75a0cbaa authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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staging: comedi: addi_apci_1564: check INSN_CONFIG_DIGITAL_TRIG shift 



commit 926234f1b8434c4409aa4c53637aa3362ca07cea 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: 1e15687e ("staging: comedi: addi_apci_1564: add Change-of-State interrupt subdevice and required functions")
Cc: <stable@vger.kernel.org> #3.17+
Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20200717145257.112660-4-abbotti@mev.co.uk


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ecceea19

drivers/staging/comedi/drivers/addi_apci_1564.c

+14 −6
Original line number Diff line number Diff line
@@ -340,14 +340,22 @@ static int apci1564_cos_insn_config(struct comedi_device *dev, 
				    unsigned int *data)

{

	struct apci1564_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;
@@ -371,8 +379,8 @@ static int apci1564_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 != (APCI1564_DI_IRQ_ENA |
@@ -389,8 +397,8 @@ static int apci1564_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;