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patch "staging: comedi: addi_apci_1564: check INSN_CONFIG_DIGITAL_TRIG shift" added to staging-linus

PATCH [email protected] 1 participant 1 message Jul 20, 2020

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This is a note to let you know that I've just added the patch titled

staging: comedi: addi_apci_1564: check INSN_CONFIG_DIGITAL_TRIG shift

to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 926234f1b8434c4409aa4c53637aa3362ca07cea Mon Sep 17 00:00:00 2001
From: Ian Abbott <[email protected]>
Date: Fri, 17 Jul 2020 15:52:56 +0100
Subject: staging: comedi: addi_apci_1564: check INSN_CONFIG_DIGITAL_TRIG shift

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 1e15687ea472 ("staging: comedi: addi_apci_1564: add Change-of-State interrupt subdevice and required functions")
Cc <[email protected]> #3.17+
Signed-off-by Ian Abbott <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 .../staging/comedi/drivers/addi_apci_1564.c   | 20 +++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)
drivers/staging/comedi/drivers/addi_apci_1564.c +14 -6
index 10501fe6bb25..1268ba34be5f 100644
@@ -331,14 +331,22 @@ 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];
-		oldmask = (1U << shift) - 1;
+		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;

@@ -362,8 +370,8 @@ 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 |

@@ -380,8 +388,8 @@ 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;
Signature · 1 line
2.27.0