ptp: only allow phase values lower than 1 period

The way we define the phase (the difference between the time of the
signal's rising edge, and the closest integer multiple of the period),
it doesn't make sense to have a phase value equal or larger than 1
period.

So deny these settings coming from the user.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index e0e6f85966e193699426f60d0e383906c34cbbf1..af3bc65c4595dd50782ff2e02a2c17d0f6d0b670 100644 (file)
--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -218,6 +218,19 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int cmd, unsigned long arg)
                                        break;
                                }
                        }
+                       if (perout->flags & PTP_PEROUT_PHASE) {
+                               /*
+                                * The phase should be specified modulo the
+                                * period, therefore anything equal or larger
+                                * than 1 period is invalid.
+                                */
+                               if (perout->phase.sec > perout->period.sec ||
+                                   (perout->phase.sec == perout->period.sec &&
+                                    perout->phase.nsec >= perout->period.nsec)) {
+                                       err = -ERANGE;
+                                       break;
+                               }
+                       }
                } else if (cmd == PTP_PEROUT_REQUEST) {
                        req.perout.flags &= PTP_PEROUT_V1_VALID_FLAGS;
                        req.perout.rsv[0] = 0;