[PATCH v3 2/2] wifi: iwlwifi: mld: Fix GP2 to nanoseconds overflow on 32-bit

[Zhan Xusheng <zhanxusheng1024@gmail.com>]

From: Zhan Xusheng <zhanxusheng@xiaomi.com>

Same problem as the mvm driver, in three places.  A GP2 timestamp is a
u32 in microseconds and NSEC_PER_USEC is 1000L, so on 32-bit

	u64 scale_time_gp2_ns = mld->ptp_data.scale_update_gp2 * NSEC_PER_USEC;
	iwl_mld_ptp_get_adj_time(mld, gp2 * NSEC_PER_USEC);
	iwl_mld_ptp_get_adj_time(mld, phy_data->gp2_on_air_rise * NSEC_PER_USEC);

are evaluated in 32 bits and truncate for any GP2 value above 4.295 s.

The last one matters most.  iwl_mld_ptp_get_adj_time() passes its
argument back to iwl_mld_ptp_update_new_read() in microseconds, which
treats a backwards step of at least IWL_PTP_WRAP_THRESHOLD_USEC as a GP2
wraparound and bumps wrap_counter.  A gp2 of 10 s truncates to a 32-bit
product of 1410065408 ns, i.e. 1410065 us, an 8589935 us step back, so
the 5000 us threshold is passed and a wraparound is recorded.  Each
spurious wraparound adds IWL_PTP_GP2_WRAP microseconds, about 71.6
minutes, to every later timestamp, and the error accumulates.

iwl_mld_ptp_gettime() and iwl_mld_phc_get_crosstimestamp() in ptp.c
already cast to u64 before multiplying.  Do the same in the three
remaining places.

Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
---
 drivers/net/wireless/intel/iwlwifi/mld/ptp.c | 5 +++--
 drivers/net/wireless/intel/iwlwifi/mld/rx.c  | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
index 1ac85d6ce1d79..41ba49f525845 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
@@ -59,7 +59,8 @@ static void iwl_mld_ptp_update_new_read(struct iwl_mld *mld, u32 gp2)
 u64 iwl_mld_ptp_get_adj_time(struct iwl_mld *mld, u64 base_time_ns)
 {
 	struct ptp_data *data = &mld->ptp_data;
-	u64 scale_time_gp2_ns = mld->ptp_data.scale_update_gp2 * NSEC_PER_USEC;
+	u64 scale_time_gp2_ns = (u64)mld->ptp_data.scale_update_gp2 *
+				NSEC_PER_USEC;
 	u64 res;
 	u64 diff;
 	s64 scaled_diff;
@@ -159,7 +160,7 @@ static int iwl_mld_ptp_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
 
 	spin_lock_bh(&data->lock);
 	data->scale_update_adj_time_ns =
-		iwl_mld_ptp_get_adj_time(mld, gp2 * NSEC_PER_USEC);
+		iwl_mld_ptp_get_adj_time(mld, (u64)gp2 * NSEC_PER_USEC);
 	data->scale_update_gp2 = gp2;
 
 	/* scale_update_adj_time_ns now relects the configured delta, the
diff --git a/drivers/net/wireless/intel/iwlwifi/mld/rx.c b/drivers/net/wireless/intel/iwlwifi/mld/rx.c
index 269439d789f46..33c8cfa95962e 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/rx.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/rx.c
@@ -1526,7 +1526,7 @@ static void iwl_mld_rx_fill_status(struct iwl_mld *mld, int link_id,
 		if (mld->monitor.ptp_time) {
 			u64 adj_time =
 				iwl_mld_ptp_get_adj_time(mld,
-							 phy_data->gp2_on_air_rise *
+							 (u64)phy_data->gp2_on_air_rise *
 							 NSEC_PER_USEC);
 
 			rx_status->mactime = div64_u64(adj_time, NSEC_PER_USEC);
-- 
2.43.0