RDMA/hns: Fix arithmetic overflow in calc_hem_config()

[ Upstream commit a38e441 ]

If bt_num is 3 or 2, then the expressions like
l0_idx * chunk_ba_num + l1_idx are computed in 32-bit
arithmetic before being assigned to a u64 index field,
which can lead to overflow.

Cast the first operand to u64 to ensure the arithmetic
is performed in 64-bit.

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

Fixes: 2f49de2 ("RDMA/hns: Optimize mhop get flow for multi-hop addressing")
Signed-off-by: Alexander Chesnokov <Alexander.Chesnokov@kaspersky.com>
Link: https://patch.msgid.link/20260413091527.39990-1-Alexander.Chesnokov@kaspersky.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Alexander Chesnokov

drivers/infiniband/hw/hns/hns_roce_hem.c

@@ -355,14 +355,14 @@ static int calc_hem_config(struct hns_roce_dev *hr_dev,
 	bt_num = hns_roce_get_bt_num(table->type, mhop->hop_num);
 	switch (bt_num) {
 	case 3:
-		index->l1 = l0_idx * chunk_ba_num + l1_idx;
+		index->l1 = (u64)l0_idx * chunk_ba_num + l1_idx;
 		index->l0 = l0_idx;
-		index->buf = l0_idx * chunk_ba_num * chunk_ba_num +
-			     l1_idx * chunk_ba_num + l2_idx;
+		index->buf = (u64)l0_idx * chunk_ba_num * chunk_ba_num +
+					 (u64)l1_idx * chunk_ba_num + l2_idx;
 		break;
 	case 2:
 		index->l0 = l0_idx;
-		index->buf = l0_idx * chunk_ba_num + l1_idx;
+		index->buf = (u64)l0_idx * chunk_ba_num + l1_idx;
 		break;
 	case 1:
 		index->buf = l0_idx;