From: Ian Abbott abbotti@mev.co.uk
commit f07804ec77d77f8a9dcf570a24154e17747bc82f upstream.
`ni6527_intr_insn_config()` processes `INSN_CONFIG` comedi instructions for the "interrupt" subdevice. When `data[0]` is `INSN_CONFIG_DIGITAL_TRIG` it is configuring the digital trigger. When `data[2]` is `COMEDI_DIGITAL_TRIG_ENABLE_EDGES` it is configuring rising and falling edge detection for the digital trigger, using a base channel number (or shift amount) in `data[3]`, a rising edge bitmask in `data[4]` and falling edge bitmask in `data[5]`.
If the base channel number (shift amount) is greater than or equal to the number of channels (24) of the digital input subdevice, there are no changes to the rising and falling edges, so the mask of channels to be changed can be set to 0, otherwise the mask of channels to be changed, and the rising and falling edge bitmasks are shifted by the base channel number before calling `ni6527_set_edge_detection()` to change the appropriate registers. Unfortunately, the code is comparing the base channel (shift amount) to the interrupt subdevice's number of channels (1) instead of the digital input subdevice's number of channels (24). Fix it by comparing to 32 because all shift amounts for an `unsigned int` must be less than that and everything from bit 24 upwards is ignored by `ni6527_set_edge_detection()` anyway.
Fixes: 110f9e687c1a8 ("staging: comedi: ni_6527: support INSN_CONFIG_DIGITAL_TRIG") Cc: stable@vger.kernel.org # 3.17+ Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/20200717145257.112660-2-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/staging/comedi/drivers/ni_6527.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/staging/comedi/drivers/ni_6527.c +++ b/drivers/staging/comedi/drivers/ni_6527.c @@ -341,7 +341,7 @@ static int ni6527_intr_insn_config(struc case COMEDI_DIGITAL_TRIG_ENABLE_EDGES: /* check shift amount */ shift = data[3]; - if (shift >= s->n_chan) { + if (shift >= 32) { mask = 0; rising = 0; falling = 0;