From: Ian Abbott abbotti@mev.co.uk
commit b4d98bc3fc93ec3a58459948a2c0e0c9b501cd88 upstream.
In `dt3k_ns_to_timer()` the following lines near the end of the function result in a signed integer overflow:
prescale = 15; base = timer_base * (1 << prescale); divider = 65535; *nanosec = divider * base;
(`divider`, `base` and `prescale` are type `int`, `timer_base` and `*nanosec` are type `unsigned int`. The value of `timer_base` will be either 50 or 100.)
The main reason for the overflow is that the calculation for `base` is completely wrong. It should be:
base = timer_base * (prescale + 1);
which matches an earlier instance of this calculation in the same function.
Reported-by: David Binderman dcb314@hotmail.com Cc: stable@vger.kernel.org Signed-off-by: Ian Abbott abbotti@mev.co.uk Link: https://lore.kernel.org/r/20190812111517.26803-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/staging/comedi/drivers/dt3000.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/staging/comedi/drivers/dt3000.c +++ b/drivers/staging/comedi/drivers/dt3000.c @@ -368,7 +368,7 @@ static int dt3k_ns_to_timer(unsigned int }
prescale = 15; - base = timer_base * (1 << prescale); + base = timer_base * (prescale + 1); divider = 65535; *nanosec = divider * base; return (prescale << 16) | (divider);