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charset="utf-8" From: Wei Fang The max_period bound in net_timer_enable_perout() was computed as: max_period =3D (u64)NETC_TMR_DEFAULT_FIPER + integral_period; which exceeds U32_MAX when integral_period > 0 (e.g. 0x100000002 for the default 333333333 Hz clock). A period_ns that passes this check but exceeds U32_MAX is then silently truncated when stored into the u32 struct netc_pp::period field. A truncated value of zero can reach netc_timer_set_perout_alarm(), where the local u32 period variable would also be 0, causing a divide-by-zero in roundup_u64(delta, period) whenever the stime < min_time branch is taken (which always happens for a start time of {0, 0}). Additionally, netc_timer_enable_periodic_pulse() and netc_timer_enable_fiper() both compute: fiper =3D pp->period - integral_period; A zero pp->period results in an unsigned wraparound to 0xFFFFFFFD, mis-programming the FIPER hardware register. Fix all three issues by capping max_period at NETC_TMR_DEFAULT_FIPER (0xFFFFFFFF). This ensures that any period_ns passing the range check fits in a u32 without truncation, so the stored value is always valid and non-zero. The accepted range is reduced by integral_period ns (typically only a few nanoseconds), which is negligible in practice. Fixes: 671e266835b8 ("ptp: netc: add periodic pulse output support") Signed-off-by: Wei Fang Reviewed-by: Abel Vesa --- v2: Remove max_period and use NETC_TMR_DEFAULT_FIPER directly --- drivers/ptp/ptp_netc.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/ptp/ptp_netc.c b/drivers/ptp/ptp_netc.c index 59db08e189e6..19ca99d80e95 100644 --- a/drivers/ptp/ptp_netc.c +++ b/drivers/ptp/ptp_netc.c @@ -440,7 +440,7 @@ static int net_timer_enable_perout(struct netc_timer *p= riv, } =20 if (on) { - u64 period_ns, gclk_period, max_period, min_period; + u64 period_ns, gclk_period, min_period; struct timespec64 period, stime; u32 integral_period; int alarm_id; @@ -450,12 +450,12 @@ static int net_timer_enable_perout(struct netc_timer = *priv, period_ns =3D timespec64_to_ns(&period); =20 integral_period =3D netc_timer_get_integral_period(priv); - max_period =3D (u64)NETC_TMR_DEFAULT_FIPER + integral_period; gclk_period =3D netc_timer_get_gclk_period(priv); min_period =3D gclk_period * 4 + integral_period; - if (period_ns > max_period || period_ns < min_period) { - dev_err(dev, "The period range is %llu ~ %llu\n", - min_period, max_period); + if (period_ns > NETC_TMR_DEFAULT_FIPER || + period_ns < min_period) { + dev_err(dev, "The period range is %llu ~ %lu\n", + min_period, NETC_TMR_DEFAULT_FIPER); err =3D -EINVAL; goto unlock_spinlock; } --=20 2.34.1