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

[Zhan Xusheng <zhanxusheng1024@gmail.com>]

GP2 is a free-running 32-bit microsecond hardware counter. The PTP code
converts a u32 GP2 value to nanoseconds as:

	gp2 * NSEC_PER_USEC

NSEC_PER_USEC is a plain 'long' (1000L), so on 32-bit builds this
multiplication is evaluated in 32-bit arithmetic and overflows once the
GP2 value exceeds ~4.29 million microseconds (~4.3 s). GP2 wraps only
every 2^32 microseconds (~71.5 min), so the product is truncated for
almost the entire counter range, producing bogus PTP timestamps.

Neighbouring conversions already cast to u64 first (e.g.
(u64)gp2 * NSEC_PER_USEC); these sites just missed the cast. Cast to u64
so the multiplication is performed in 64-bit, matching the existing call
sites. 64-bit builds are unaffected.

Fixes: d1e879ec600f ("wifi: iwlwifi: add iwlmld sub-driver")
Fixes: f1699ad5857d ("wifi: iwlwifi: mld: add debugfs for using ptp clock time for monitor interface")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
---
 drivers/net/wireless/intel/iwlwifi/mld/ptp.c | 4 ++--
 drivers/net/wireless/intel/iwlwifi/mld/rx.c  | 6 ++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
index 1ac85d6ce1d7..81645f8caa54 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/ptp.c
@@ -59,7 +59,7 @@ 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 +159,7 @@ 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 269439d789f4..108ac70bfb14 100644
--- a/drivers/net/wireless/intel/iwlwifi/mld/rx.c
+++ b/drivers/net/wireless/intel/iwlwifi/mld/rx.c
@@ -1524,10 +1524,8 @@ static void iwl_mld_rx_fill_status(struct iwl_mld *mld, int link_id,
 		iwl_mld_add_rtap_sniffer_config(mld, skb);
 
 		if (mld->monitor.ptp_time) {
-			u64 adj_time =
-				iwl_mld_ptp_get_adj_time(mld,
-							 phy_data->gp2_on_air_rise *
-							 NSEC_PER_USEC);
+			u64 gp2_ns = (u64)phy_data->gp2_on_air_rise * NSEC_PER_USEC;
+			u64 adj_time = iwl_mld_ptp_get_adj_time(mld, gp2_ns);
 
 			rx_status->mactime = div64_u64(adj_time, NSEC_PER_USEC);
 			rx_status->flag |= RX_FLAG_MACTIME_IS_RTAP_TS64;
-- 
2.43.0