[PATCH 5.15.y] gve: Fix stats report corruption on queue count change

[Sasha Levin <sashal@kernel.org>]

From: Debarghya Kundu <debarghyak@google.com>

[ Upstream commit 7b9ebcce0296e104a0d82a6b09d68564806158ff ]

The driver and the NIC share a region in memory for stats reporting.
The NIC calculates its offset into this region based on the total size
of the stats region and the size of the NIC's stats.

When the number of queues is changed, the driver's stats region is
resized. If the queue count is increased, the NIC can write past
the end of the allocated stats region, causing memory corruption.
If the queue count is decreased, there is a gap between the driver
and NIC stats, leading to incorrect stats reporting.

This change fixes the issue by allocating stats region with maximum
size, and the offset calculation for NIC stats is changed to match
with the calculation of the NIC.

Cc: stable@vger.kernel.org
Fixes: 24aeb56f2d38 ("gve: Add Gvnic stats AQ command and ethtool show/set-priv-flags.")
Signed-off-by: Debarghya Kundu <debarghyak@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20260202193925.3106272-2-hramamurthy@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Same changes as 6.1 + context ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/google/gve/gve_ethtool.c | 42 +++++++++++++------
 drivers/net/ethernet/google/gve/gve_main.c    |  4 +-
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index 1f8cc722aae30..19d4520d1d9c5 100644
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -142,7 +142,8 @@ gve_get_ethtool_stats(struct net_device *netdev,
 		tmp_rx_desc_err_dropped_pkt, tmp_tx_pkts, tmp_tx_bytes;
 	u64 rx_buf_alloc_fail, rx_desc_err_dropped_pkt, rx_pkts,
 		rx_skb_alloc_fail, rx_bytes, tx_pkts, tx_bytes;
-	int stats_idx, base_stats_idx, max_stats_idx;
+	int rx_base_stats_idx, max_rx_stats_idx, max_tx_stats_idx;
+	int stats_idx, stats_region_len, nic_stats_len;
 	struct stats *report_stats;
 	int *rx_qid_to_stats_idx;
 	int *tx_qid_to_stats_idx;
@@ -228,14 +229,33 @@ gve_get_ethtool_stats(struct net_device *netdev,
 	data[i++] = priv->stats_report_trigger_cnt;
 	i = GVE_MAIN_STATS_LEN;
 
-	/* For rx cross-reporting stats, start from nic rx stats in report */
-	base_stats_idx = GVE_TX_STATS_REPORT_NUM * priv->tx_cfg.num_queues +
-		GVE_RX_STATS_REPORT_NUM * priv->rx_cfg.num_queues;
-	max_stats_idx = NIC_RX_STATS_REPORT_NUM * priv->rx_cfg.num_queues +
-		base_stats_idx;
+	rx_base_stats_idx = 0;
+	max_rx_stats_idx = 0;
+	max_tx_stats_idx = 0;
+	stats_region_len = priv->stats_report_len -
+				sizeof(struct gve_stats_report);
+	nic_stats_len = (NIC_RX_STATS_REPORT_NUM * priv->rx_cfg.num_queues +
+		NIC_TX_STATS_REPORT_NUM * priv->tx_cfg.num_queues) *
+		sizeof(struct stats);
+	if (unlikely((stats_region_len -
+				nic_stats_len) % sizeof(struct stats))) {
+		net_err_ratelimited("Starting index of NIC stats should be multiple of stats size");
+	} else {
+		/* For rx cross-reporting stats,
+		 * start from nic rx stats in report
+		 */
+		rx_base_stats_idx = (stats_region_len - nic_stats_len) /
+							sizeof(struct stats);
+		max_rx_stats_idx = NIC_RX_STATS_REPORT_NUM *
+			priv->rx_cfg.num_queues +
+			rx_base_stats_idx;
+		max_tx_stats_idx = NIC_TX_STATS_REPORT_NUM *
+			priv->tx_cfg.num_queues +
+			max_rx_stats_idx;
+	}
 	/* Preprocess the stats report for rx, map queue id to start index */
 	skip_nic_stats = false;
-	for (stats_idx = base_stats_idx; stats_idx < max_stats_idx;
+	for (stats_idx = rx_base_stats_idx; stats_idx < max_rx_stats_idx;
 		stats_idx += NIC_RX_STATS_REPORT_NUM) {
 		u32 stat_name = be32_to_cpu(report_stats[stats_idx].stat_name);
 		u32 queue_id = be32_to_cpu(report_stats[stats_idx].queue_id);
@@ -288,13 +308,9 @@ gve_get_ethtool_stats(struct net_device *netdev,
 		i += priv->rx_cfg.num_queues * NUM_GVE_RX_CNTS;
 	}
 
-	/* For tx cross-reporting stats, start from nic tx stats in report */
-	base_stats_idx = max_stats_idx;
-	max_stats_idx = NIC_TX_STATS_REPORT_NUM * priv->tx_cfg.num_queues +
-		max_stats_idx;
-	/* Preprocess the stats report for tx, map queue id to start index */
 	skip_nic_stats = false;
-	for (stats_idx = base_stats_idx; stats_idx < max_stats_idx;
+	/* NIC TX stats start right after NIC RX stats */
+	for (stats_idx = max_rx_stats_idx; stats_idx < max_tx_stats_idx;
 		stats_idx += NIC_TX_STATS_REPORT_NUM) {
 		u32 stat_name = be32_to_cpu(report_stats[stats_idx].stat_name);
 		u32 queue_id = be32_to_cpu(report_stats[stats_idx].queue_id);
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 9e10806890577..a8fb51e77fea0 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -135,9 +135,9 @@ static int gve_alloc_stats_report(struct gve_priv *priv)
 	int tx_stats_num, rx_stats_num;
 
 	tx_stats_num = (GVE_TX_STATS_REPORT_NUM + NIC_TX_STATS_REPORT_NUM) *
-		       priv->tx_cfg.num_queues;
+				priv->tx_cfg.max_queues;
 	rx_stats_num = (GVE_RX_STATS_REPORT_NUM + NIC_RX_STATS_REPORT_NUM) *
-		       priv->rx_cfg.num_queues;
+				priv->rx_cfg.max_queues;
 	priv->stats_report_len = struct_size(priv->stats_report, stats,
 					     size_add(tx_stats_num, rx_stats_num));
 	priv->stats_report =
-- 
2.51.0