From: Ian Abbott abbotti@mev.co.uk
commit fc846e9db67c7e808d77bf9e2ef3d49e3820ce5d 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, adjusting the checks for invalid channels so that enabled channel bits that would have been lost by shifting are also checked for validity. Only channels 0 to 15 are valid.
Fixes: a8c66b684efaf ("staging: comedi: addi_apci_1500: rewrite the subdevice support functions") Cc: stable@vger.kernel.org #4.0+: ef75e14a6c93: staging: comedi: verify array index is correct before using it Cc: stable@vger.kernel.org #4.0+ Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/20200717145257.112660-5-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- .../staging/comedi/drivers/addi_apci_1500.c | 24 +++++++++++++++---- 1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/staging/comedi/drivers/addi_apci_1500.c b/drivers/staging/comedi/drivers/addi_apci_1500.c index 689acd69a1b9..816dd25b9d0e 100644 --- a/drivers/staging/comedi/drivers/addi_apci_1500.c +++ b/drivers/staging/comedi/drivers/addi_apci_1500.c @@ -452,13 +452,14 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev, struct apci1500_private *devpriv = dev->private; unsigned int trig = data[1]; unsigned int shift = data[3]; - unsigned int hi_mask = data[4] << shift; - unsigned int lo_mask = data[5] << shift; - unsigned int chan_mask = hi_mask | lo_mask; - unsigned int old_mask = (1 << shift) - 1; + unsigned int hi_mask; + unsigned int lo_mask; + unsigned int chan_mask; + unsigned int old_mask; unsigned int pm; unsigned int pt; unsigned int pp; + unsigned int invalid_chan;
if (trig > 1) { dev_dbg(dev->class_dev, @@ -466,7 +467,20 @@ static int apci1500_di_cfg_trig(struct comedi_device *dev, return -EINVAL; }
- if (chan_mask > 0xffff) { + if (shift <= 16) { + hi_mask = data[4] << shift; + lo_mask = data[5] << shift; + old_mask = (1U << shift) - 1; + invalid_chan = (data[4] | data[5]) >> (16 - shift); + } else { + hi_mask = 0; + lo_mask = 0; + old_mask = 0xffff; + invalid_chan = data[4] | data[5]; + } + chan_mask = hi_mask | lo_mask; + + if (invalid_chan) { dev_dbg(dev->class_dev, "invalid digital trigger channel\n"); return -EINVAL; }