This code reads from the array before verifying that "trig" is a valid
index. If the index is wildly out of bounds then reading from an
invalid address could lead to an Oops.
Fixes: a8c66b684efa ("staging: comedi: addi_apci_1500: rewrite the subdevice support functions")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
drivers/staging/comedi/drivers/addi_apci_1500.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/comedi/drivers/addi_apci_1500.c b/drivers/staging/comedi/drivers/addi_apci_1500.c
index 45ad4ba92f94..689acd69a1b9 100644
--- a/drivers/staging/comedi/drivers/addi_apci_1500.c
+++ b/drivers/staging/comedi/drivers/addi_apci_1500.c
@@ -456,9 +456,9 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev,
unsigned int lo_mask = data[5] << shift;
unsigned int chan_mask = hi_mask | lo_mask;
unsigned int old_mask = (1 << shift) - 1;
- unsigned int pm = devpriv->pm[trig] & old_mask;
- unsigned int pt = devpriv->pt[trig] & old_mask;
- unsigned int pp = devpriv->pp[trig] & old_mask;
+ unsigned int pm;
+ unsigned int pt;
+ unsigned int pp;
if (trig > 1) {
dev_dbg(dev->class_dev,
@@ -471,6 +471,10 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev,
return -EINVAL;
}
+ pm = devpriv->pm[trig] & old_mask;
+ pt = devpriv->pt[trig] & old_mask;
+ pp = devpriv->pp[trig] & old_mask;
+
switch (data[2]) {
case COMEDI_DIGITAL_TRIG_DISABLE:
/* clear trigger configuration */
--
2.27.0
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