net: hns3: fix out-of-bounds access may occur when coalesce info is read via debugfs

The hns3 driver define an array of string to show the coalesce
info, but if the kernel adds a new mode or a new state,
out-of-bounds access may occur when coalesce info is read via
debugfs, this patch fix the problem.

Fixes: c99fead7 ("net: hns3: add debugfs support for interrupt coalesce")
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Signed-off-by: Jijie Shao <shaojijie@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/hisilicon/hns3/hns3_debugfs.c

@@ -503,11 +503,14 @@ static void hns3_get_coal_info(struct hns3_enet_tqp_vector *tqp_vector,
 	}
 
 	sprintf(result[j++], "%d", i);
-	sprintf(result[j++], "%s", dim_state_str[dim->state]);
+	sprintf(result[j++], "%s", dim->state < ARRAY_SIZE(dim_state_str) ?
+		dim_state_str[dim->state] : "unknown");
 	sprintf(result[j++], "%u", dim->profile_ix);
-	sprintf(result[j++], "%s", dim_cqe_mode_str[dim->mode]);
+	sprintf(result[j++], "%s", dim->mode < ARRAY_SIZE(dim_cqe_mode_str) ?
+		dim_cqe_mode_str[dim->mode] : "unknown");
 	sprintf(result[j++], "%s",
-		dim_tune_stat_str[dim->tune_state]);
+		dim->tune_state < ARRAY_SIZE(dim_tune_stat_str) ?
+		dim_tune_stat_str[dim->tune_state] : "unknown");
 	sprintf(result[j++], "%u", dim->steps_left);
 	sprintf(result[j++], "%u", dim->steps_right);
 	sprintf(result[j++], "%u", dim->tired);