[PATCH net-next] ptp: only allow phase values lower than 1 period

Vladimir Oltean
2020-08-03T19:49:34Z

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 larger than 1 period.

So deny these settings coming from the user.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
---
drivers/ptp/ptp_chardev.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
index e0e6f85966e1..02fcd5e8b998 100644
--- 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 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;
--
2.25.1