[PATCH] wifi: mt76: mt7915: fix possible integer overflows in mt7915_muru_stats_show()

[Nikita Zhandarovich]

Assuming sums of values stored in variables such as sub_total_cnt
and total_ppdu_cnt are big enough to warrant their u64 type, it
makes sense to ensure that their calculation takes into account
possible integer overflow issues.

Play it safe and fix the problem by casting right hand expressions
to u64 as well. Also, slightly adjust tabulation.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: 1966a5078f2d ("mt76: mt7915: add mu-mimo and ofdma debugfs knobs")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@xxxxxxxxxx>
---
 .../net/wireless/mediatek/mt76/mt7915/debugfs.c    | 45 +++++++++++-----------
 1 file changed, 23 insertions(+), 22 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c b/drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c
index 578013884e43..4fec7d000a63 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7915/debugfs.c
@@ -303,9 +303,9 @@ static int mt7915_muru_stats_show(struct seq_file *file, void *data)
 		   phy->mib.dl_vht_3mu_cnt,
 		   phy->mib.dl_vht_4mu_cnt);
 
-	sub_total_cnt = phy->mib.dl_vht_2mu_cnt +
-			phy->mib.dl_vht_3mu_cnt +
-			phy->mib.dl_vht_4mu_cnt;
+	sub_total_cnt = (u64)phy->mib.dl_vht_2mu_cnt +
+			     phy->mib.dl_vht_3mu_cnt +
+			     phy->mib.dl_vht_4mu_cnt;
 
 	seq_printf(file, "\nTotal non-HE MU-MIMO DL PPDU count: %lld",
 		   sub_total_cnt);
@@ -353,26 +353,27 @@ static int mt7915_muru_stats_show(struct seq_file *file, void *data)
 		   phy->mib.dl_he_9to16ru_cnt,
 		   phy->mib.dl_he_gtr16ru_cnt);
 
-	sub_total_cnt = phy->mib.dl_he_2mu_cnt +
-			phy->mib.dl_he_3mu_cnt +
-			phy->mib.dl_he_4mu_cnt;
+	sub_total_cnt = (u64)phy->mib.dl_he_2mu_cnt +
+			     phy->mib.dl_he_3mu_cnt +
+			     phy->mib.dl_he_4mu_cnt;
 	total_ppdu_cnt = sub_total_cnt;
 
 	seq_printf(file, "\nTotal HE MU-MIMO DL PPDU count: %lld",
 		   sub_total_cnt);
 
-	sub_total_cnt = phy->mib.dl_he_2ru_cnt +
-			phy->mib.dl_he_3ru_cnt +
-			phy->mib.dl_he_4ru_cnt +
-			phy->mib.dl_he_5to8ru_cnt +
-			phy->mib.dl_he_9to16ru_cnt +
-			phy->mib.dl_he_gtr16ru_cnt;
+	sub_total_cnt = (u64)phy->mib.dl_he_2ru_cnt +
+			     phy->mib.dl_he_3ru_cnt +
+			     phy->mib.dl_he_4ru_cnt +
+			     phy->mib.dl_he_5to8ru_cnt +
+			     phy->mib.dl_he_9to16ru_cnt +
+			     phy->mib.dl_he_gtr16ru_cnt;
 	total_ppdu_cnt += sub_total_cnt;
 
 	seq_printf(file, "\nTotal HE OFDMA DL PPDU count: %lld",
 		   sub_total_cnt);
 
-	total_ppdu_cnt += phy->mib.dl_he_su_cnt + phy->mib.dl_he_ext_su_cnt;
+	total_ppdu_cnt += (u64)phy->mib.dl_he_su_cnt +
+			       phy->mib.dl_he_ext_su_cnt;
 
 	seq_printf(file, "\nAll HE DL PPDU count: %lld", total_ppdu_cnt);
 
@@ -404,20 +405,20 @@ static int mt7915_muru_stats_show(struct seq_file *file, void *data)
 		   phy->mib.ul_hetrig_9to16ru_cnt,
 		   phy->mib.ul_hetrig_gtr16ru_cnt);
 
-	sub_total_cnt = phy->mib.ul_hetrig_2mu_cnt +
-			phy->mib.ul_hetrig_3mu_cnt +
-			phy->mib.ul_hetrig_4mu_cnt;
+	sub_total_cnt = (u64)phy->mib.ul_hetrig_2mu_cnt +
+			     phy->mib.ul_hetrig_3mu_cnt +
+			     phy->mib.ul_hetrig_4mu_cnt;
 	total_ppdu_cnt = sub_total_cnt;
 
 	seq_printf(file, "\nTotal HE MU-MIMO UL TB PPDU count: %lld",
 		   sub_total_cnt);
 
-	sub_total_cnt = phy->mib.ul_hetrig_2ru_cnt +
-			phy->mib.ul_hetrig_3ru_cnt +
-			phy->mib.ul_hetrig_4ru_cnt +
-			phy->mib.ul_hetrig_5to8ru_cnt +
-			phy->mib.ul_hetrig_9to16ru_cnt +
-			phy->mib.ul_hetrig_gtr16ru_cnt;
+	sub_total_cnt = (u64)phy->mib.ul_hetrig_2ru_cnt +
+			     phy->mib.ul_hetrig_3ru_cnt +
+			     phy->mib.ul_hetrig_4ru_cnt +
+			     phy->mib.ul_hetrig_5to8ru_cnt +
+			     phy->mib.ul_hetrig_9to16ru_cnt +
+			     phy->mib.ul_hetrig_gtr16ru_cnt;
 	total_ppdu_cnt += sub_total_cnt;
 
 	seq_printf(file, "\nTotal HE OFDMA UL TB PPDU count: %lld",