[PATCH net v2] net: airoha: fix BQL underflow and UAF in shared QDMA TX ring
Lorenzo Bianconi
lorenzo at kernel.org
Fri Jun 19 03:30:28 PDT 2026
When multiple netdevs share a QDMA TX ring and one device is stopped,
netdev_tx_reset_subqueue() zeroes that device's BQL counters while its
pending skbs remain in the shared HW TX ring. When NAPI later completes
those skbs via netdev_tx_completed_queue(), the already-zeroed
dql->num_queued counter underflows.
Moreover, in the airoha_remove() path, netdevs are unregistered
sequentially while skbs from previously unregistered netdevs may still
reference freed net_device memory via skb->dev, causing a use-after-free
during BQL accounting.
Fix both issues:
- Remove netdev_tx_reset_subqueue() from airoha_dev_stop() so pending
skbs are completed naturally by NAPI with proper BQL accounting.
- Introduce airoha_qdma_tx_flush() to stop NAPI and flush BQL counters
for all pending skbs while skb->dev references are still valid.
- Guard airoha_dev_xmit() with DEV_STATE_FLUSH to drop packets during
teardown.
- Move DMA engine start into probe and stop into airoha_qdma_cleanup().
Fixes: a9c2ca61fec7 ("net: airoha: Support multiple net_devices for a single FE GDM port")
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
Changes in v2:
- Introduce airoha_qdma_tx_flush() to account BQL in airoha_remove() or
airoha_probe() error path.
- Fix possible NULL pointer dereference in airoha_qdma_cleanup().
- Introduce DEV_STATE_FLUSH().
- Move back airoha_hw_cleanup().
- Set proper Fixes tag.
- Link to v1: https://lore.kernel.org/r/20260618-airoha-bql-fixes-v1-1-ffd2c2089518@kernel.org
---
drivers/net/ethernet/airoha/airoha_eth.c | 87 +++++++++++++++++++++++---------
drivers/net/ethernet/airoha/airoha_eth.h | 1 +
2 files changed, 63 insertions(+), 25 deletions(-)
diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 64dde6464f3f..e81cd806b57b 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -1004,6 +1004,7 @@ static int airoha_qdma_tx_napi_poll(struct napi_struct *napi, int budget)
e = &q->entry[index];
skb = e->skb;
+ e->skb = NULL;
dma_unmap_single(eth->dev, e->dma_addr, e->dma_len,
DMA_TO_DEVICE);
@@ -1523,10 +1524,26 @@ static int airoha_qdma_init(struct platform_device *pdev,
return airoha_qdma_hw_init(qdma);
}
-static void airoha_qdma_cleanup(struct airoha_qdma *qdma)
+static void airoha_qdma_cleanup(struct airoha_eth *eth,
+ struct airoha_qdma *qdma)
{
int i;
+ if (test_bit(DEV_STATE_INITIALIZED, ð->state)) {
+ u32 status;
+
+ airoha_qdma_clear(qdma, REG_QDMA_GLOBAL_CFG,
+ GLOBAL_CFG_TX_DMA_EN_MASK |
+ GLOBAL_CFG_RX_DMA_EN_MASK);
+ if (read_poll_timeout(airoha_qdma_rr, status,
+ !(status & (GLOBAL_CFG_TX_DMA_BUSY_MASK |
+ GLOBAL_CFG_RX_DMA_BUSY_MASK)),
+ USEC_PER_MSEC, 50 * USEC_PER_MSEC, true,
+ qdma, REG_QDMA_GLOBAL_CFG))
+ dev_warn(eth->dev,
+ "QDMA DMA engine busy timeout\n");
+ }
+
for (i = 0; i < ARRAY_SIZE(qdma->q_rx); i++) {
if (!qdma->q_rx[i].ndesc)
continue;
@@ -1593,7 +1610,7 @@ static int airoha_hw_init(struct platform_device *pdev,
return 0;
error:
for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
- airoha_qdma_cleanup(ð->qdma[i]);
+ airoha_qdma_cleanup(eth, ð->qdma[i]);
return err;
}
@@ -1603,7 +1620,7 @@ static void airoha_hw_cleanup(struct airoha_eth *eth)
int i;
for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
- airoha_qdma_cleanup(ð->qdma[i]);
+ airoha_qdma_cleanup(eth, ð->qdma[i]);
airoha_ppe_deinit(eth);
}
@@ -1637,6 +1654,35 @@ static void airoha_qdma_stop_napi(struct airoha_qdma *qdma)
}
}
+static void airoha_qdma_tx_flush(struct airoha_qdma *qdma)
+{
+ int i;
+
+ airoha_qdma_stop_napi(qdma);
+
+ for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++) {
+ struct airoha_queue *q = &qdma->q_tx[i];
+ int j;
+
+ if (!q->ndesc)
+ continue;
+
+ spin_lock_bh(&q->lock);
+ for (j = 0; j < q->ndesc; j++) {
+ struct airoha_queue_entry *e = &q->entry[j];
+ struct sk_buff *skb = e->skb;
+ struct netdev_queue *txq;
+
+ if (!skb)
+ continue;
+
+ txq = skb_get_tx_queue(skb->dev, skb);
+ netdev_tx_completed_queue(txq, 1, skb->len);
+ }
+ spin_unlock_bh(&q->lock);
+ }
+}
+
static void airoha_dev_get_hw_stats(struct airoha_gdm_dev *dev)
{
struct airoha_gdm_port *port = dev->port;
@@ -1837,9 +1883,6 @@ static int airoha_dev_open(struct net_device *netdev)
}
port->users++;
- airoha_qdma_set(qdma, REG_QDMA_GLOBAL_CFG,
- GLOBAL_CFG_TX_DMA_EN_MASK |
- GLOBAL_CFG_RX_DMA_EN_MASK);
qdma->users++;
if (!airoha_is_lan_gdm_dev(dev) &&
@@ -1880,12 +1923,9 @@ static int airoha_dev_stop(struct net_device *netdev)
struct airoha_gdm_dev *dev = netdev_priv(netdev);
struct airoha_gdm_port *port = dev->port;
struct airoha_qdma *qdma = dev->qdma;
- int i;
netif_tx_disable(netdev);
airoha_set_vip_for_gdm_port(dev, false);
- for (i = 0; i < netdev->num_tx_queues; i++)
- netdev_tx_reset_subqueue(netdev, i);
if (--port->users)
airoha_set_port_mtu(dev->eth, port);
@@ -1893,19 +1933,7 @@ static int airoha_dev_stop(struct net_device *netdev)
airoha_set_gdm_port_fwd_cfg(qdma->eth,
REG_GDM_FWD_CFG(port->id),
FE_PSE_PORT_DROP);
-
- if (!--qdma->users) {
- airoha_qdma_clear(qdma, REG_QDMA_GLOBAL_CFG,
- GLOBAL_CFG_TX_DMA_EN_MASK |
- GLOBAL_CFG_RX_DMA_EN_MASK);
-
- for (i = 0; i < ARRAY_SIZE(qdma->q_tx); i++) {
- if (!qdma->q_tx[i].ndesc)
- continue;
-
- airoha_qdma_cleanup_tx_queue(&qdma->q_tx[i]);
- }
- }
+ qdma->users--;
return 0;
}
@@ -2191,6 +2219,9 @@ static netdev_tx_t airoha_dev_xmit(struct sk_buff *skb,
u16 index;
u8 fport;
+ if (test_bit(DEV_STATE_FLUSH, &dev->eth->state))
+ goto error;
+
qid = airoha_qdma_get_txq(qdma, skb_get_queue_mapping(skb));
tag = airoha_get_dsa_tag(skb, netdev);
@@ -3413,8 +3444,12 @@ static int airoha_probe(struct platform_device *pdev)
if (err)
goto error_netdev_free;
- for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
+ for (i = 0; i < ARRAY_SIZE(eth->qdma); i++) {
airoha_qdma_start_napi(ð->qdma[i]);
+ airoha_qdma_set(ð->qdma[i], REG_QDMA_GLOBAL_CFG,
+ GLOBAL_CFG_TX_DMA_EN_MASK |
+ GLOBAL_CFG_RX_DMA_EN_MASK);
+ }
for_each_child_of_node(pdev->dev.of_node, np) {
if (!of_device_is_compatible(np, "airoha,eth-mac"))
@@ -3437,8 +3472,9 @@ static int airoha_probe(struct platform_device *pdev)
return 0;
error_napi_stop:
+ set_bit(DEV_STATE_FLUSH, ð->state);
for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
- airoha_qdma_stop_napi(ð->qdma[i]);
+ airoha_qdma_tx_flush(ð->qdma[i]);
for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
struct airoha_gdm_port *port = eth->ports[i];
@@ -3474,8 +3510,9 @@ static void airoha_remove(struct platform_device *pdev)
struct airoha_eth *eth = platform_get_drvdata(pdev);
int i;
+ set_bit(DEV_STATE_FLUSH, ð->state);
for (i = 0; i < ARRAY_SIZE(eth->qdma); i++)
- airoha_qdma_stop_napi(ð->qdma[i]);
+ airoha_qdma_tx_flush(ð->qdma[i]);
for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
struct airoha_gdm_port *port = eth->ports[i];
diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
index 41d2e7a1f9fb..f6dce5e74e02 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.h
+++ b/drivers/net/ethernet/airoha/airoha_eth.h
@@ -92,6 +92,7 @@ enum {
enum {
DEV_STATE_INITIALIZED,
DEV_STATE_REGISTERED,
+ DEV_STATE_FLUSH,
};
enum {
---
base-commit: a887f2c7da66a805a55fd8706d45faec85f646db
change-id: 20260618-airoha-bql-fixes-f57b2d108573
Best regards,
--
Lorenzo Bianconi <lorenzo at kernel.org>
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