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Subject[PATCH v2] staging/comedi: Fix undefined array subscript
Date
In vmk80xx_do_insn_bits the local variable reg, which is used as an
index to the tx_buf array, can be used uninitialized if
- data[0] == 0
and
- devpriv->model != VMK8061_MODEL
-> we get into the else branch without having reg initialized.

Since the driver usually differentiates between VMK8061_MODEL and
VMK8055_MODEL it's safe to assume that VMK8055_DO_REG was meant as an
initial value.

And to avoid duplication we can move the assignments to the top.

Acked-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
drivers/staging/comedi/drivers/vmk80xx.c | 17 +++++++----------
1 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/comedi/drivers/vmk80xx.c b/drivers/staging/comedi/drivers/vmk80xx.c
index ebf2d48..eed46ee 100644
--- a/drivers/staging/comedi/drivers/vmk80xx.c
+++ b/drivers/staging/comedi/drivers/vmk80xx.c
@@ -675,8 +675,14 @@ static int vmk80xx_do_insn_bits(struct comedi_device *dev,
if (data[0])
dir |= DIR_OUT;

- if (devpriv->model == VMK8061_MODEL)
+ if (devpriv->model == VMK8061_MODEL) {
dir |= DIR_IN;
+ reg = VMK8061_DO_REG;
+ cmd = VMK8061_CMD_DO;
+ } else { /* VMK8055_MODEL */
+ reg = VMK8055_DO_REG;
+ cmd = VMK8055_CMD_WRT_AD;
+ }

retval = rudimentary_check(devpriv, dir);
if (retval)
@@ -688,14 +694,6 @@ static int vmk80xx_do_insn_bits(struct comedi_device *dev,
tx_buf = devpriv->usb_tx_buf;

if (data[0]) {
- if (devpriv->model == VMK8055_MODEL) {
- reg = VMK8055_DO_REG;
- cmd = VMK8055_CMD_WRT_AD;
- } else { /* VMK8061_MODEL */
- reg = VMK8061_DO_REG;
- cmd = VMK8061_CMD_DO;
- }
-
tx_buf[reg] &= ~data[0];
tx_buf[reg] |= (data[0] & data[1]);

@@ -706,7 +704,6 @@ static int vmk80xx_do_insn_bits(struct comedi_device *dev,
}

if (devpriv->model == VMK8061_MODEL) {
- reg = VMK8061_DO_REG;
tx_buf[0] = VMK8061_CMD_RD_DO;

retval = vmk80xx_read_packet(devpriv);
--
1.7.8.6


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