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Commit 5afdcad2 authored by Ian Abbott's avatar Ian Abbott Committed by Greg Kroah-Hartman
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staging: comedi: comedi_test: limit maximum convert_arg 



When testing the parameters for setting up an asynchronous command on
the AI subdevice, limit the maximum conversion period
(`cmd->convert_arg`) so that the number of conversions in a scan
(`cmd->scan_end_arg`, same as `cmd->chanlist_len`) multiplied by the
conversion period fits within an `unsigned int`, as that is used to
limit the minimum scan period (`cmd->scan_begin_arg`).

Also ensure rounding of the conversion period and scan period to the
nearest microsecond both fit in an `unsigned int`.  Do all this in stage
4 ("fix up any arguments") of the command testing.

Signed-off-by: default avatarIan Abbott <abbotti@mev.co.uk>
Reviewed-by: default avatarH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 87f64803

drivers/staging/comedi/drivers/comedi_test.c

+21 −21
Original line number Diff line number Diff line
@@ -234,7 +234,7 @@ static int waveform_ai_cmdtest(struct comedi_device *dev, 
			       struct comedi_cmd *cmd)

{

	int err = 0;

	unsigned int arg;

	unsigned int arg, limit;



	/* Step 1 : check if triggers are trivially valid */
@@ -265,16 +265,8 @@ static int waveform_ai_cmdtest(struct comedi_device *dev, 
	if (cmd->convert_src == TRIG_NOW)

		err |= comedi_check_trigger_arg_is(&cmd->convert_arg, 0);



	if (cmd->scan_begin_src == TRIG_TIMER) {

	err |= comedi_check_trigger_arg_min(&cmd->scan_begin_arg,

					    NSEC_PER_USEC);

		if (cmd->convert_src == TRIG_TIMER) {

			err |= comedi_check_trigger_arg_min(&cmd->

							    scan_begin_arg,

							    cmd->convert_arg *

							    cmd->chanlist_len);

		}

	}



	err |= comedi_check_trigger_arg_min(&cmd->chanlist_len, 1);

	err |= comedi_check_trigger_arg_is(&cmd->scan_end_arg,
@@ -290,21 +282,29 @@ static int waveform_ai_cmdtest(struct comedi_device *dev, 


	/* step 4: fix up any arguments */



	if (cmd->scan_begin_src == TRIG_TIMER) {

		arg = cmd->scan_begin_arg;

		/* round to nearest microsec */

		arg = NSEC_PER_USEC *

		      ((arg + (NSEC_PER_USEC / 2)) / NSEC_PER_USEC);

		err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);

	}

	if (cmd->convert_src == TRIG_TIMER) {

		/* round convert_arg to nearest microsecond */

		arg = cmd->convert_arg;

		/* round to nearest microsec */

		arg = NSEC_PER_USEC *

		      ((arg + (NSEC_PER_USEC / 2)) / NSEC_PER_USEC);

		arg = min(arg,

			  rounddown(UINT_MAX, (unsigned int)NSEC_PER_USEC));

		arg = NSEC_PER_USEC * DIV_ROUND_CLOSEST(arg, NSEC_PER_USEC);

		/* limit convert_arg to keep scan_begin_arg in range */

		limit = UINT_MAX / cmd->scan_end_arg;

		limit = rounddown(limit, (unsigned int)NSEC_PER_SEC);

		arg = min(arg, limit);

		err |= comedi_check_trigger_arg_is(&cmd->convert_arg, arg);

	}



	/* round scan_begin_arg to nearest microsecond */

	arg = cmd->scan_begin_arg;

	arg = min(arg, rounddown(UINT_MAX, (unsigned int)NSEC_PER_USEC));

	arg = NSEC_PER_USEC * DIV_ROUND_CLOSEST(arg, NSEC_PER_USEC);

	if (cmd->convert_src == TRIG_TIMER) {

		/* but ensure scan_begin_arg is large enough */

		arg = max(arg, cmd->convert_arg * cmd->scan_end_arg);

	}

	err |= comedi_check_trigger_arg_is(&cmd->scan_begin_arg, arg);



	if (err)

		return 4;