staging: comedi: cb_pcidas64: fix possible integer overflow

The {min,max}_scan_divisor values could overflow due to the
unsigned int * insigned int calculation. Change the type of the
local variable 'convert_divisor' to unsigned long long to avoid
the possible overflow.

Reported-by: coverity (CID 200653)
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/comedi/drivers/cb_pcidas64.c b/drivers/staging/comedi/drivers/cb_pcidas64.c
index 5b43e4e6d037793ca295d05c2420e8bf3c64857b..9836c877c91020d6fda6ddea6b967581c33efd96 100644 (file)
--- a/drivers/staging/comedi/drivers/cb_pcidas64.c
+++ b/drivers/staging/comedi/drivers/cb_pcidas64.c
@@ -2001,7 +2001,8 @@ static unsigned int get_divisor(unsigned int ns, unsigned int flags)
 static void check_adc_timing(struct comedi_device *dev, struct comedi_cmd *cmd)
 {
        const struct pcidas64_board *thisboard = dev->board_ptr;
-       unsigned int convert_divisor = 0, scan_divisor;
+       unsigned long long convert_divisor = 0;
+       unsigned int scan_divisor;
        static const int min_convert_divisor = 3;
        static const int max_convert_divisor =
                max_counter_value + min_convert_divisor;
@@ -2027,7 +2028,6 @@ static void check_adc_timing(struct comedi_device *dev, struct comedi_cmd *cmd)
        if (cmd->scan_begin_src == TRIG_TIMER) {
                scan_divisor = get_divisor(cmd->scan_begin_arg, cmd->flags);
                if (cmd->convert_src == TRIG_TIMER) {
-                       /*  XXX check for integer overflows */
                        min_scan_divisor = convert_divisor * cmd->chanlist_len;
                        max_scan_divisor =
                                (convert_divisor * cmd->chanlist_len - 1) +