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* [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko
@ 2026-10-23 20:47 Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 1/4] gve: Fix race between stats query and queue reconfig Harshitha Ramamurthy
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Harshitha Ramamurthy @ 2026-10-23 20:47 UTC (permalink / raw)
  To: netdev
  Cc: joshwash, hramamurthy, andrew+netdev, davem, edumazet, kuba,
	pabeni, jordanrhee, willemb, przemyslaw.kitszel, nktgrg, maolson,
	jacob.e.keller, pkaligineedi, yangchun, patricion, awogbemila,
	stable, linux-kernel, Pin-yen Lin

From: Pin-yen Lin <treapking@google.com>

This patch series addresses several issues in the gve driver. All four of
these fixes were either uncovered by running the net selftests or
suggested by Sashiko in the previous version.

The series includes the following changes:

- Patch 1 introduces a spinlock (stats_lock) to robustly synchronize stats
  queries (including ndo_get_stats64 and queue stats) against queue
  teardown and restart, preventing UAF and out-of-bounds reads. This was
  discovered by the drivers/net/stats.py selftest.
- Patch 2 fixes an issue where interface stats would go backwards when the
  interface was brought down or its configuration was adjusted. This was
  also discovered by the drivers/net/stats.py selftest.
- Patch 3 ensures the driver falls back to the default minimum ring size if
  the corresponding device option values are exposed as 0. This prevents
  userspace from configuring unexpectedly small ring sizes. This was
  discovered by the drivers/net/ring_reconfig.py selftest.
- Patch 4 makes sure ethtool configuration modifications are done
  synchronously before returning to the userspace. This was discovered by
  the drivers/net/ping.py selftest.

Changes in v3:
- Link to v2: https://lore.kernel.org/netdev/20260425002450.163421-1-hramamurthy@google.com/
- Protect all stats queries and queue lifecycle updates with a spinlock
  (Sashiko)
- Drop u64_stats_sync for the base stats and use the spinlock instead
- Save base stats in gve_queues_mem_remove() and gve_rx_queue_stop()
- Drop unused rx_dropped and tx_dropped accumulation in
  gve_add_base_stats()
- Fix the Fixes tag of patch 4
- Refined the commit messages
- Rebased to the latest net tree

Changes in v2:
- Add a NULL pointer check in gve_get_ring_err_stats() (Sashiko)
- Use local variable to prevent inflates from u64_stats_fetch_retry()
  (Sashiko)
- Add u64_stats_fetch/begin to protect base stats (Sashiko)

Debarghya Kundu (1):
  gve: Fix backward stats when interface goes down or configuration is
    adjusted

Pin-yen Lin (3):
  gve: Fix race between stats query and queue reconfig
  gve: Block invalid ring sizes when device options are 0
  gve: Fix link flap after ethtool ops

 drivers/net/ethernet/google/gve/gve.h        |   8 +
 drivers/net/ethernet/google/gve/gve_adminq.c |   4 +-
 drivers/net/ethernet/google/gve/gve_main.c   | 179 ++++++++++++++-----
 3 files changed, 148 insertions(+), 43 deletions(-)


base-commit: 734bef548a96e8774d6eef5dfa2026c6edc4e80b
-- 
2.56.0.257.gf7497c7d27-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net v3 1/4] gve: Fix race between stats query and queue reconfig
  2026-10-23 20:47 [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko Harshitha Ramamurthy
@ 2026-10-23 20:47 ` Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 2/4] gve: Fix backward stats when interface goes down or configuration is adjusted Harshitha Ramamurthy
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 5+ messages in thread
From: Harshitha Ramamurthy @ 2026-10-23 20:47 UTC (permalink / raw)
  To: netdev
  Cc: joshwash, hramamurthy, andrew+netdev, davem, edumazet, kuba,
	pabeni, jordanrhee, willemb, przemyslaw.kitszel, nktgrg, maolson,
	jacob.e.keller, pkaligineedi, yangchun, patricion, awogbemila,
	stable, linux-kernel, Pin-yen Lin, Debarghya Kundu

From: Pin-yen Lin <treapking@google.com>

Fix a concurrency bug where network statistics queries race with queue
reconfiguration or interface teardown, causing a Use-After-Free (UAF) or
NULL pointer dereference.

Currently, statistics queries access priv->tx and priv->rx without
locking. When an interface is brought down or reconfigured,
gve_queues_mem_remove() frees these arrays. A concurrent stats query
can dereference freed queue structures and crash the kernel.

This issue was discovered and actually triggered by the
drivers/net/stats.py selftest. When an interface was brought down,
querying per-queue statistics via Netlink caused a kernel NULL pointer
dereference in gve_get_rx_queue_stats():

  BUG: kernel NULL pointer dereference, address: 00000000000000a0
  RIP: 0010:gve_get_rx_queue_stats+0x17/0x50 [gve]
  Call Trace:
   <TASK>
   netdev_stat_queue_sum+0x11c/0x250
   netdev_nl_stats_by_netdev+0x21b/0x2d0
   netdev_nl_qstats_get_dumpit+0xd2/0x220
   genl_dumpit+0x32/0x90
   netlink_dump+0x1d2/0x450
   __netlink_dump_start+0x1db/0x2a0
   genl_family_rcv_msg_dumpit+0x9b/0x100
   ...

Additionally, concurrent stats queries during queue reconfiguration can
race with gve_queues_mem_remove(), causing a Use-After-Free.

Fix this by introducing stats_lock to serialize stats queries against
queue teardown. In gve_queues_mem_remove(), queue pointers are set to
NULL under stats_lock before freeing. Stats readers acquire the lock
and verify pointers are non-NULL before reading counters.

This change was tested using the DQO RDA queue format.

Cc: stable@vger.kernel.org
Fixes: 2e5e0932dff5 ("gve: add support for basic queue stats")
Co-developed-by: Debarghya Kundu <debarghyak@google.com>
Signed-off-by: Debarghya Kundu <debarghyak@google.com>
Signed-off-by: Pin-yen Lin <treapking@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---

Changes in v3:
- Retitled from "gve: Add NULL pointer checks for per-queue statistics"
- Protect all stats queries and queue lifecycle updates with spinlock
  (sashiko)
- Refined the commit message

 drivers/net/ethernet/google/gve/gve.h      |  2 ++
 drivers/net/ethernet/google/gve/gve_main.c | 37 +++++++++++++++++++---
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index b7ce6e8632db..104468c2c07f 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -957,6 +957,8 @@ struct gve_priv {
 	struct workqueue_struct *gve_wq;
 	struct work_struct service_task;
 	struct work_struct stats_report_task;
+	/* Synchronizes stats accesses and queue teardown */
+	spinlock_t stats_lock;
 	unsigned long service_task_flags;
 	unsigned long state_flags;
 
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 2437cd8ba633..26fdd22644f4 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -69,6 +69,7 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
 	int num_tx_queues;
 	int ring;
 
+	spin_lock_bh(&priv->stats_lock);
 	num_tx_queues = gve_num_tx_queues(priv);
 	if (priv->rx) {
 		for (ring = 0; ring < priv->rx_cfg.num_queues; ring++) {
@@ -96,6 +97,7 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
 			s->tx_bytes += bytes;
 		}
 	}
+	spin_unlock_bh(&priv->stats_lock);
 }
 
 static int gve_alloc_flow_rule_caches(struct gve_priv *priv)
@@ -642,9 +644,13 @@ static void gve_queues_mem_remove(struct gve_priv *priv)
 	struct gve_rx_alloc_rings_cfg rx_alloc_cfg = {0};
 
 	gve_get_curr_alloc_cfgs(priv, &tx_alloc_cfg, &rx_alloc_cfg);
-	gve_queues_mem_free(priv, &tx_alloc_cfg, &rx_alloc_cfg);
+
+	spin_lock_bh(&priv->stats_lock);
 	priv->tx = NULL;
 	priv->rx = NULL;
+	spin_unlock_bh(&priv->stats_lock);
+
+	gve_queues_mem_free(priv, &tx_alloc_cfg, &rx_alloc_cfg);
 }
 
 static void gve_free_control_plane_resources(struct gve_priv *priv)
@@ -1383,6 +1389,7 @@ static int gve_queues_start(struct gve_priv *priv,
 	int err;
 
 	/* Record new resources into priv */
+	spin_lock_bh(&priv->stats_lock);
 	priv->tx = tx_alloc_cfg->tx;
 	priv->rx = rx_alloc_cfg->rx;
 
@@ -1396,10 +1403,11 @@ static int gve_queues_start(struct gve_priv *priv,
 	priv->rx_pages_per_qpl = rx_alloc_cfg->pages_per_qpl;
 	priv->header_split_enabled = rx_alloc_cfg->enable_header_split;
 	priv->rx_cfg.packet_buffer_size = rx_alloc_cfg->packet_buffer_size;
+	gve_init_sync_stats(priv);
+	spin_unlock_bh(&priv->stats_lock);
 
 	gve_tx_start_rings(priv, gve_num_tx_queues(priv));
 	gve_rx_start_rings(priv, rx_alloc_cfg->qcfg_rx->num_queues);
-	gve_init_sync_stats(priv);
 
 	err = netif_set_real_num_tx_queues(dev, priv->tx_cfg.num_queues);
 	if (err)
@@ -2266,6 +2274,7 @@ void gve_handle_report_stats(struct gve_priv *priv)
 	if (!gve_get_report_stats(priv))
 		return;
 
+	spin_lock_bh(&priv->stats_lock);
 	be64_add_cpu(&priv->stats_report->written_count, 1);
 	/* tx stats */
 	if (priv->tx) {
@@ -2330,6 +2339,7 @@ void gve_handle_report_stats(struct gve_priv *priv)
 			};
 		}
 	}
+	spin_unlock_bh(&priv->stats_lock);
 }
 
 /* Handle NIC status register changes, reset requests and report stats */
@@ -2786,9 +2796,15 @@ static void gve_get_rx_queue_stats(struct net_device *dev, int idx,
 				   struct netdev_queue_stats_rx *rx_stats)
 {
 	struct gve_priv *priv = netdev_priv(dev);
-	struct gve_rx_ring *rx = &priv->rx[idx];
+	struct gve_rx_ring *rx;
 	unsigned int start;
 
+	spin_lock_bh(&priv->stats_lock);
+	if (!priv->rx)
+		goto unlock;
+
+	rx = &priv->rx[idx];
+
 	do {
 		start = u64_stats_fetch_begin(&rx->statss);
 		rx_stats->packets = rx->rpackets;
@@ -2796,20 +2812,32 @@ static void gve_get_rx_queue_stats(struct net_device *dev, int idx,
 		rx_stats->alloc_fail = rx->rx_skb_alloc_fail +
 				       rx->rx_buf_alloc_fail;
 	} while (u64_stats_fetch_retry(&rx->statss, start));
+
+unlock:
+	spin_unlock_bh(&priv->stats_lock);
 }
 
 static void gve_get_tx_queue_stats(struct net_device *dev, int idx,
 				   struct netdev_queue_stats_tx *tx_stats)
 {
 	struct gve_priv *priv = netdev_priv(dev);
-	struct gve_tx_ring *tx = &priv->tx[idx];
+	struct gve_tx_ring *tx;
 	unsigned int start;
 
+	spin_lock_bh(&priv->stats_lock);
+	if (!priv->tx)
+		goto unlock;
+
+	tx = &priv->tx[idx];
+
 	do {
 		start = u64_stats_fetch_begin(&tx->statss);
 		tx_stats->packets = tx->pkt_done;
 		tx_stats->bytes = tx->bytes_done;
 	} while (u64_stats_fetch_retry(&tx->statss, start));
+
+unlock:
+	spin_unlock_bh(&priv->stats_lock);
 }
 
 static void gve_get_base_stats(struct net_device *dev,
@@ -2935,6 +2963,7 @@ static int gve_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 	INIT_WORK(&priv->service_task, gve_service_task);
 	INIT_WORK(&priv->stats_report_task, gve_stats_report_task);
+	spin_lock_init(&priv->stats_lock);
 	priv->tx_cfg.max_queues = max_tx_queues;
 	priv->rx_cfg.max_queues = max_rx_queues;
 
-- 
2.56.0.257.gf7497c7d27-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net v3 2/4] gve: Fix backward stats when interface goes down or configuration is adjusted
  2026-10-23 20:47 [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 1/4] gve: Fix race between stats query and queue reconfig Harshitha Ramamurthy
@ 2026-10-23 20:47 ` Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 3/4] gve: Block invalid ring sizes when device options are 0 Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 4/4] gve: Fix link flap after ethtool ops Harshitha Ramamurthy
  3 siblings, 0 replies; 5+ messages in thread
From: Harshitha Ramamurthy @ 2026-10-23 20:47 UTC (permalink / raw)
  To: netdev
  Cc: joshwash, hramamurthy, andrew+netdev, davem, edumazet, kuba,
	pabeni, jordanrhee, willemb, przemyslaw.kitszel, nktgrg, maolson,
	jacob.e.keller, pkaligineedi, yangchun, patricion, awogbemila,
	stable, linux-kernel, Debarghya Kundu, Pin-yen Lin

From: Debarghya Kundu <debarghyak@google.com>

gve_get_base_stats() sets all the stats to 0, so the stats go backwards
when interface goes down or configuration is adjusted.

This issue was discovered and actually triggered by the
drivers/net/stats.py selftest (check_down test case). Bringing down the
interface caused statistics counters to reset to 0, triggering selftest
assertion failures because netdevice stats must not go backwards.

Fix this by persisting baseline stats across queue teardown in
gve_queues_mem_remove() and single-queue stop in gve_rx_queue_stop().

This change was tested using the DQO RDA queue format.

Cc: stable@vger.kernel.org
Fixes: 2e5e0932dff5 ("gve: add support for basic queue stats")
Signed-off-by: Debarghya Kundu <debarghyak@google.com>
Co-developed-by: Pin-yen Lin <treapking@google.com>
Signed-off-by: Pin-yen Lin <treapking@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---

Changes in v3:
- Drop u64_stats_sync for the base stats and use spinlock to protect
  them instead
- Save base stats in gve_queues_mem_remove() instead of gve_close()
- Save base stats in gve_rx_queue_stop() for single-queue restarts
- Drop unused rx_dropped and tx_dropped accumulation in gve_add_base_stats()
- Refined the commit message

Changes in v2:
- Add a NULL pointer check in gve_get_ring_err_stats() (Sashiko)
- Use local variable to prevent inflates from u64_stats_fetch_retry()
  (Sashiko)
- Add u64_stats_fetch/begin to protect base stats (Sashiko)

 drivers/net/ethernet/google/gve/gve.h      |  6 ++
 drivers/net/ethernet/google/gve/gve_main.c | 83 +++++++++++++++++++---
 2 files changed, 81 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index 104468c2c07f..37070bc14c87 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -871,6 +871,10 @@ struct gve_ctrl_ops {
 	int (*report_link_speed)(struct gve_priv *priv);
 };
 
+struct gve_ring_err_stats {
+	u64 rx_alloc_fails;
+};
+
 struct gve_priv {
 	struct net_device *dev;
 	struct gve_tx_ring *tx; /* array of tx_cfg.num_queues */
@@ -962,6 +966,8 @@ struct gve_priv {
 	unsigned long service_task_flags;
 	unsigned long state_flags;
 
+	struct gve_ring_err_stats base_ring_err_stats;
+	struct rtnl_link_stats64 base_net_stats;
 	struct gve_stats_report *stats_report;
 	u64 stats_report_len;
 	dma_addr_t stats_report_bus; /* dma address for the stats report */
diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 26fdd22644f4..52c152a986eb 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -61,15 +61,25 @@ static netdev_tx_t gve_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		return gve_tx_dqo(skb, dev);
 }
 
-static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
+static void gve_add_base_stats(struct gve_priv *priv,
+			       struct rtnl_link_stats64 *s)
+{
+	struct rtnl_link_stats64 *base_stats = &priv->base_net_stats;
+
+	s->rx_packets += base_stats->rx_packets;
+	s->rx_bytes += base_stats->rx_bytes;
+	s->tx_packets += base_stats->tx_packets;
+	s->tx_bytes += base_stats->tx_bytes;
+}
+
+static void gve_get_ring_stats(struct gve_priv *priv,
+			       struct rtnl_link_stats64 *s)
 {
-	struct gve_priv *priv = netdev_priv(dev);
 	unsigned int start;
 	u64 packets, bytes;
 	int num_tx_queues;
 	int ring;
 
-	spin_lock_bh(&priv->stats_lock);
 	num_tx_queues = gve_num_tx_queues(priv);
 	if (priv->rx) {
 		for (ring = 0; ring < priv->rx_cfg.num_queues; ring++) {
@@ -97,6 +107,38 @@ static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
 			s->tx_bytes += bytes;
 		}
 	}
+}
+
+static void gve_get_ring_err_stats(struct gve_priv *priv,
+				   struct gve_ring_err_stats *err_stats)
+{
+	int ring;
+
+	if (!priv->rx)
+		return;
+
+	for (ring = 0; ring < priv->rx_cfg.num_queues; ring++) {
+		struct gve_rx_ring *rx = &priv->rx[ring];
+		unsigned int start;
+		u64 rx_alloc_fails;
+
+		do {
+			start = u64_stats_fetch_begin(&rx->statss);
+			rx_alloc_fails = rx->rx_skb_alloc_fail +
+					 rx->rx_buf_alloc_fail;
+		} while (u64_stats_fetch_retry(&rx->statss, start));
+
+		err_stats->rx_alloc_fails += rx_alloc_fails;
+	}
+}
+
+static void gve_get_stats(struct net_device *dev, struct rtnl_link_stats64 *s)
+{
+	struct gve_priv *priv = netdev_priv(dev);
+
+	spin_lock_bh(&priv->stats_lock);
+	gve_get_ring_stats(priv, s);
+	gve_add_base_stats(priv, s);
 	spin_unlock_bh(&priv->stats_lock);
 }
 
@@ -646,6 +688,9 @@ static void gve_queues_mem_remove(struct gve_priv *priv)
 	gve_get_curr_alloc_cfgs(priv, &tx_alloc_cfg, &rx_alloc_cfg);
 
 	spin_lock_bh(&priv->stats_lock);
+	gve_get_ring_stats(priv, &priv->base_net_stats);
+	gve_get_ring_err_stats(priv, &priv->base_ring_err_stats);
+
 	priv->tx = NULL;
 	priv->rx = NULL;
 	spin_unlock_bh(&priv->stats_lock);
@@ -2689,8 +2734,20 @@ static int gve_rx_queue_stop(struct net_device *dev, void *per_q_mem, int idx)
 	gve_turnup_and_check_status(priv);
 
 	gve_per_q_mem = (struct gve_rx_ring *)per_q_mem;
+	spin_lock_bh(&priv->stats_lock);
+	priv->base_net_stats.rx_packets += priv->rx[idx].rpackets;
+	priv->base_net_stats.rx_bytes += priv->rx[idx].rbytes;
+	priv->base_ring_err_stats.rx_alloc_fails +=
+		priv->rx[idx].rx_skb_alloc_fail +
+		priv->rx[idx].rx_buf_alloc_fail;
 	*gve_per_q_mem = priv->rx[idx];
 	memset(&priv->rx[idx], 0, sizeof(priv->rx[idx]));
+	spin_unlock_bh(&priv->stats_lock);
+
+	gve_per_q_mem->rpackets = 0;
+	gve_per_q_mem->rbytes = 0;
+	gve_per_q_mem->rx_skb_alloc_fail = 0;
+	gve_per_q_mem->rx_buf_alloc_fail = 0;
 	return 0;
 }
 
@@ -2844,12 +2901,22 @@ static void gve_get_base_stats(struct net_device *dev,
 			       struct netdev_queue_stats_rx *rx,
 			       struct netdev_queue_stats_tx *tx)
 {
-	rx->packets = 0;
-	rx->bytes = 0;
-	rx->alloc_fail = 0;
+	const struct gve_ring_err_stats *base_err_stats;
+	const struct rtnl_link_stats64 *base_stats;
+	struct gve_priv *priv;
+
+	priv = netdev_priv(dev);
+	base_stats = &priv->base_net_stats;
+	base_err_stats = &priv->base_ring_err_stats;
+
+	spin_lock_bh(&priv->stats_lock);
+	rx->packets = base_stats->rx_packets;
+	rx->bytes = base_stats->rx_bytes;
+	rx->alloc_fail = base_err_stats->rx_alloc_fails;
 
-	tx->packets = 0;
-	tx->bytes = 0;
+	tx->packets = base_stats->tx_packets;
+	tx->bytes = base_stats->tx_bytes;
+	spin_unlock_bh(&priv->stats_lock);
 }
 
 static const struct netdev_stat_ops gve_stat_ops = {
-- 
2.56.0.257.gf7497c7d27-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net v3 3/4] gve: Block invalid ring sizes when device options are 0
  2026-10-23 20:47 [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 1/4] gve: Fix race between stats query and queue reconfig Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 2/4] gve: Fix backward stats when interface goes down or configuration is adjusted Harshitha Ramamurthy
@ 2026-10-23 20:47 ` Harshitha Ramamurthy
  2026-10-23 20:47 ` [PATCH net v3 4/4] gve: Fix link flap after ethtool ops Harshitha Ramamurthy
  3 siblings, 0 replies; 5+ messages in thread
From: Harshitha Ramamurthy @ 2026-10-23 20:47 UTC (permalink / raw)
  To: netdev
  Cc: joshwash, hramamurthy, andrew+netdev, davem, edumazet, kuba,
	pabeni, jordanrhee, willemb, przemyslaw.kitszel, nktgrg, maolson,
	jacob.e.keller, pkaligineedi, yangchun, patricion, awogbemila,
	stable, linux-kernel, Pin-yen Lin

From: Pin-yen Lin <treapking@google.com>

On older device versions, minimum ring sizes in the device option are
reported as 0. The driver imports these 0 values, allowing userspace
(`ethtool -G`) to request invalidly small ring sizes.

This issue was discovered and actually triggered by the
drivers/net/ring_reconfig.py selftest (ringparam test case). Halving the
ring size down to 1 triggered a kernel NULL pointer dereference in
gve_tx_alloc_rings_dqo():

  BUG: kernel NULL pointer dereference, address: 0000000000000002
  RIP: 0010:gve_tx_alloc_rings_dqo+0x1c4/0x510 [gve]
  Call Trace:
   <TASK>
   gve_queues_mem_alloc+0x29/0xa0 [gve]
   gve_adjust_config+0x1b/0x140 [gve]
   gve_set_ringparam+0x1f4/0x250 [gve]
   ethnl_set_rings+0x260/0x440
   ...

Fix this by falling back to the driver's default minimum ring sizes
(GVE_DEFAULT_MIN_RX_RING_SIZE and GVE_DEFAULT_MIN_TX_RING_SIZE) whenever
the device option reports minimum ring sizes as 0.

This change was tested using the DQO RDA queue format.

Cc: stable@vger.kernel.org
Fixes: ed4fb326947d ("gve: add support to read ring size ranges from the device")
Signed-off-by: Pin-yen Lin <treapking@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
Reviewed-by: Jordan Rhee <jordanrhee@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---

Changes in v3:
- Retitled and refined the commit message

 drivers/net/ethernet/google/gve/gve_adminq.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 8b215fca9c1b..2c848f0c23dc 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -191,7 +191,9 @@ void gve_parse_device_option(struct gve_priv *priv,
 		*dev_op_modify_ring = (void *)(option + 1);
 
 		/* device has not provided min ring size */
-		if (option_length == GVE_DEVICE_OPTION_NO_MIN_RING_SIZE)
+		if (option_length == GVE_DEVICE_OPTION_NO_MIN_RING_SIZE ||
+		    be16_to_cpu((*dev_op_modify_ring)->min_rx_ring_size) == 0 ||
+		    be16_to_cpu((*dev_op_modify_ring)->min_tx_ring_size) == 0)
 			priv->device_info.default_min_ring_size = true;
 		break;
 	case GVE_DEV_OPT_ID_FLOW_STEERING:
-- 
2.56.0.257.gf7497c7d27-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

* [PATCH net v3 4/4] gve: Fix link flap after ethtool ops
  2026-10-23 20:47 [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko Harshitha Ramamurthy
                   ` (2 preceding siblings ...)
  2026-10-23 20:47 ` [PATCH net v3 3/4] gve: Block invalid ring sizes when device options are 0 Harshitha Ramamurthy
@ 2026-10-23 20:47 ` Harshitha Ramamurthy
  3 siblings, 0 replies; 5+ messages in thread
From: Harshitha Ramamurthy @ 2026-10-23 20:47 UTC (permalink / raw)
  To: netdev
  Cc: joshwash, hramamurthy, andrew+netdev, davem, edumazet, kuba,
	pabeni, jordanrhee, willemb, przemyslaw.kitszel, nktgrg, maolson,
	jacob.e.keller, pkaligineedi, yangchun, patricion, awogbemila,
	stable, linux-kernel, Pin-yen Lin

From: Pin-yen Lin <treapking@google.com>

When modifying device features via ethtool, GVE causes a short link-down
after the ethtool command completes, which can break scripts that use
the network interface right after the ethtool command.

This issue was discovered and actually triggered by the
drivers/net/ping.py selftest. Modifying checksum offload features via
ethtool caused a transient carrier drop ("Lost carrier", DHCP lease lost),
causing the immediate ping invocation to fail.

Fix it by calling gve_turnup_and_check_status() in gve_queues_start()
instead of deferring the link status update to the service task, so the
carrier status is updated synchronously before returning to userspace.

This change was tested using the DQO RDA queue format.

Cc: stable@vger.kernel.org
Fixes: 3b7cc73628ff ("gve: Use link status register to report link status")
Signed-off-by: Pin-yen Lin <treapking@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
---

Changes in v3:
- Retitled from "gve: Make ethtool config changes synchronous"
- Fix the Fixes tag
- Refined the commit message

 drivers/net/ethernet/google/gve/gve_main.c | 61 +++++++++++-----------
 1 file changed, 30 insertions(+), 31 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 52c152a986eb..e2a016f4430a 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -1423,6 +1423,35 @@ static void gve_queues_stop(struct gve_priv *priv)
 	gve_rx_stop_rings(priv, priv->rx_cfg.num_queues);
 }
 
+static void gve_handle_link_status(struct gve_priv *priv)
+{
+	bool link_up;
+
+	if (!gve_get_napi_enabled(priv))
+		return;
+
+	link_up = READ_ONCE(priv->link_up);
+	if (link_up == netif_carrier_ok(priv->dev))
+		return;
+
+	if (link_up) {
+		netdev_info(priv->dev, "Device link is up.\n");
+		netif_carrier_on(priv->dev);
+	} else {
+		netdev_info(priv->dev, "Device link is down.\n");
+		netif_carrier_off(priv->dev);
+	}
+}
+
+static void gve_turnup_and_check_status(struct gve_priv *priv)
+{
+	const struct gve_ctrl_ops *ops = priv->ctrl_ops;
+
+	gve_turnup(priv);
+	ops->report_link_status(priv);
+	gve_handle_link_status(priv);
+}
+
 /* The passed-in queue memory is stored into priv and the queues are made live.
  * No memory is allocated. Passed-in memory is freed on errors.
  */
@@ -1486,8 +1515,7 @@ static int gve_queues_start(struct gve_priv *priv,
 			  round_jiffies(jiffies +
 				msecs_to_jiffies(priv->stats_report_timer_period)));
 
-	gve_turnup(priv);
-	queue_work(priv->gve_wq, &priv->service_task);
+	gve_turnup_and_check_status(priv);
 	priv->interface_up_cnt++;
 	return 0;
 
@@ -1562,26 +1590,6 @@ static int gve_close(struct net_device *dev)
 	return err;
 }
 
-static void gve_handle_link_status(struct gve_priv *priv)
-{
-	bool link_up;
-
-	if (!gve_get_napi_enabled(priv))
-		return;
-
-	link_up = READ_ONCE(priv->link_up);
-	if (link_up == netif_carrier_ok(priv->dev))
-		return;
-
-	if (link_up) {
-		netdev_info(priv->dev, "Device link is up.\n");
-		netif_carrier_on(priv->dev);
-	} else {
-		netdev_info(priv->dev, "Device link is down.\n");
-		netif_carrier_off(priv->dev);
-	}
-}
-
 static int gve_configure_rings_xdp(struct gve_priv *priv,
 				   u16 num_xdp_rings)
 {
@@ -2056,15 +2064,6 @@ static void gve_turnup(struct gve_priv *priv)
 	gve_set_napi_enabled(priv);
 }
 
-static void gve_turnup_and_check_status(struct gve_priv *priv)
-{
-	const struct gve_ctrl_ops *ops = priv->ctrl_ops;
-
-	gve_turnup(priv);
-	ops->report_link_status(priv);
-	gve_handle_link_status(priv);
-}
-
 static struct gve_notify_block *gve_get_tx_notify_block(struct gve_priv *priv,
 							unsigned int txqueue)
 {
-- 
2.56.0.257.gf7497c7d27-goog


^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2026-10-23 20:47 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2026-10-23 20:47 [PATCH net v3 0/4] gve: Fixes for issues discovered via net selftests and Sashiko Harshitha Ramamurthy
2026-10-23 20:47 ` [PATCH net v3 1/4] gve: Fix race between stats query and queue reconfig Harshitha Ramamurthy
2026-10-23 20:47 ` [PATCH net v3 2/4] gve: Fix backward stats when interface goes down or configuration is adjusted Harshitha Ramamurthy
2026-10-23 20:47 ` [PATCH net v3 3/4] gve: Block invalid ring sizes when device options are 0 Harshitha Ramamurthy
2026-10-23 20:47 ` [PATCH net v3 4/4] gve: Fix link flap after ethtool ops Harshitha Ramamurthy

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