[PATCH net-next v5 10/19] net: stmmac: fix error path cleanup in DMA descriptor ring allocation

[James Hilliard <james.hilliard1@gmail.com>]

From: Ding Hui <dinghui@lixiang.com>

__alloc_dma_rx_desc_resources() and __alloc_dma_tx_desc_resources()
allocate resources in multiple steps but return early on failure
without cleaning up what they have already allocated. The outer
error paths then call the free helpers on partially-initialized
queues, which dereference pointers that were never allocated:

  - dma_free_rx_skbufs() and dma_free_rx_xskbufs() dereference
    rx_q->buf_pool[i] via stmmac_free_rx_buffer(), but buf_pool
    may be NULL if its kzalloc_objs() failed.

  - dma_free_tx_skbufs() dereferences tx_q->tx_skbuff_dma[i] via
    stmmac_free_tx_buffer(), but tx_skbuff_dma may be NULL if its
    kzalloc_objs() failed.

  - stmmac_free_tx_buffer() dereferences tx_q->xdpf[i] and
    tx_q->tx_skbuff[i] (aliased through a union), but tx_skbuff
    may be NULL if its allocation failed while tx_skbuff_dma
    succeeded.

Fix this by making each allocation function responsible for undoing
its own allocations on error, following the standard kernel error
handling pattern of cleaning up in reverse order. Also add NULL
checks in the free helpers as a defensive measure, since they may
be called on partially-initialized queues.
Additionally, make __free_dma_rx_desc_resources() and
__free_dma_tx_desc_resources() clear the pointers they free, so that
the NULL guards in the free helpers hold reliably when the long-lived
priv->dma_conf is reused across XDP open/release cycles.

Signed-off-by: Ding Hui <dinghui@lixiang.com>
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 70 +++++++++++++++++++----
 1 file changed, 60 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index d9d676ae1c82..258de45d122c 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1767,7 +1767,7 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv,
 					 DMA_TO_DEVICE);
 	}
 
-	if (tx_q->xdpf[i] &&
+	if (tx_q->xdpf && tx_q->xdpf[i] &&
 	    (tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_TX ||
 	     tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XDP_NDO)) {
 		xdp_return_frame(tx_q->xdpf[i]);
@@ -1777,7 +1777,7 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv,
 	if (tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_XSK_TX)
 		tx_q->xsk_frames_done++;
 
-	if (tx_q->tx_skbuff[i] &&
+	if (tx_q->tx_skbuff && tx_q->tx_skbuff[i] &&
 	    tx_q->tx_skbuff_dma[i].buf_type == STMMAC_TXBUF_T_SKB) {
 		dev_kfree_skb_any(tx_q->tx_skbuff[i]);
 		tx_q->tx_skbuff[i] = NULL;
@@ -1800,6 +1800,10 @@ static void dma_free_rx_skbufs(struct stmmac_priv *priv,
 	struct stmmac_rx_queue *rx_q = &dma_conf->rx_queue[queue];
 	int i;
 
+	/* buf_pool may not be allocated if alloc failed early */
+	if (!rx_q->buf_pool)
+		return;
+
 	for (i = 0; i < dma_conf->dma_rx_size; i++)
 		stmmac_free_rx_buffer(priv, rx_q, i);
 }
@@ -1841,6 +1845,10 @@ static void dma_free_rx_xskbufs(struct stmmac_priv *priv,
 	struct stmmac_rx_queue *rx_q = &dma_conf->rx_queue[queue];
 	int i;
 
+	/* buf_pool may not be allocated if alloc failed early */
+	if (!rx_q->buf_pool)
+		return;
+
 	for (i = 0; i < dma_conf->dma_rx_size; i++) {
 		struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
 
@@ -2136,6 +2144,10 @@ static void dma_free_tx_skbufs(struct stmmac_priv *priv,
 	struct stmmac_tx_queue *tx_q = &dma_conf->tx_queue[queue];
 	int i;
 
+	/* tx_skbuff_dma may not be allocated if alloc failed early */
+	if (!tx_q->tx_skbuff_dma)
+		return;
+
 	tx_q->xsk_frames_done = 0;
 
 	for (i = 0; i < dma_conf->dma_tx_size; i++)
@@ -2193,13 +2205,20 @@ static void __free_dma_rx_desc_resources(struct stmmac_priv *priv,
 	size = stmmac_get_rx_desc_size(priv) * dma_conf->dma_rx_size;
 
 	dma_free_coherent(priv->device, size, addr, rx_q->dma_rx_phy);
+	rx_q->dma_erx = NULL;
+	rx_q->dma_rx = NULL;
+	rx_q->dma_rx_phy = 0;
 
 	if (xdp_rxq_info_is_reg(&rx_q->xdp_rxq))
 		xdp_rxq_info_unreg(&rx_q->xdp_rxq);
 
 	kfree(rx_q->buf_pool);
-	if (rx_q->page_pool)
+	rx_q->buf_pool = NULL;
+
+	if (rx_q->page_pool) {
 		page_pool_destroy(rx_q->page_pool);
+		rx_q->page_pool = NULL;
+	}
 }
 
 static void free_dma_rx_desc_resources(struct stmmac_priv *priv,
@@ -2241,9 +2260,16 @@ static void __free_dma_tx_desc_resources(struct stmmac_priv *priv,
 	size = stmmac_get_tx_desc_size(priv, tx_q) * dma_conf->dma_tx_size;
 
 	dma_free_coherent(priv->device, size, addr, tx_q->dma_tx_phy);
+	tx_q->dma_etx = NULL;
+	tx_q->dma_entx = NULL;
+	tx_q->dma_tx = NULL;
+	tx_q->dma_tx_phy = 0;
 
 	kfree(tx_q->tx_skbuff_dma);
+	tx_q->tx_skbuff_dma = NULL;
+
 	kfree(tx_q->tx_skbuff);
+	tx_q->tx_skbuff = NULL;
 }
 
 static void free_dma_tx_desc_resources(struct stmmac_priv *priv,
@@ -2311,15 +2337,19 @@ static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
 	}
 
 	rx_q->buf_pool = kzalloc_objs(*rx_q->buf_pool, dma_conf->dma_rx_size);
-	if (!rx_q->buf_pool)
-		return -ENOMEM;
+	if (!rx_q->buf_pool) {
+		ret = -ENOMEM;
+		goto err_destroy_pool;
+	}
 
 	size = stmmac_get_rx_desc_size(priv) * dma_conf->dma_rx_size;
 
 	addr = dma_alloc_coherent(priv->device, size, &rx_q->dma_rx_phy,
 				  GFP_KERNEL);
-	if (!addr)
-		return -ENOMEM;
+	if (!addr) {
+		ret = -ENOMEM;
+		goto err_free_buf_pool;
+	}
 
 	if (priv->extend_desc)
 		rx_q->dma_erx = addr;
@@ -2335,10 +2365,22 @@ static int __alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
 	ret = xdp_rxq_info_reg(&rx_q->xdp_rxq, priv->dev, queue, napi_id);
 	if (ret) {
 		netdev_err(priv->dev, "Failed to register xdp rxq info\n");
-		return -EINVAL;
+		goto err_free_dma;
 	}
 
 	return 0;
+
+err_free_dma:
+	dma_free_coherent(priv->device, size, addr, rx_q->dma_rx_phy);
+	rx_q->dma_erx = NULL;
+	rx_q->dma_rx = NULL;
+err_free_buf_pool:
+	kfree(rx_q->buf_pool);
+	rx_q->buf_pool = NULL;
+err_destroy_pool:
+	page_pool_destroy(rx_q->page_pool);
+	rx_q->page_pool = NULL;
+	return ret;
 }
 
 static int alloc_dma_rx_desc_resources(struct stmmac_priv *priv,
@@ -2391,14 +2433,14 @@ static int __alloc_dma_tx_desc_resources(struct stmmac_priv *priv,
 
 	tx_q->tx_skbuff = kzalloc_objs(struct sk_buff *, dma_conf->dma_tx_size);
 	if (!tx_q->tx_skbuff)
-		return -ENOMEM;
+		goto err_free_skbuff_dma;
 
 	size = stmmac_get_tx_desc_size(priv, tx_q) * dma_conf->dma_tx_size;
 
 	addr = dma_alloc_coherent(priv->device, size,
 				  &tx_q->dma_tx_phy, GFP_KERNEL);
 	if (!addr)
-		return -ENOMEM;
+		goto err_free_skbuff;
 
 	if (priv->extend_desc)
 		tx_q->dma_etx = addr;
@@ -2408,6 +2450,14 @@ static int __alloc_dma_tx_desc_resources(struct stmmac_priv *priv,
 		tx_q->dma_tx = addr;
 
 	return 0;
+
+err_free_skbuff:
+	kfree(tx_q->tx_skbuff);
+	tx_q->tx_skbuff = NULL;
+err_free_skbuff_dma:
+	kfree(tx_q->tx_skbuff_dma);
+	tx_q->tx_skbuff_dma = NULL;
+	return -ENOMEM;
 }
 
 static int alloc_dma_tx_desc_resources(struct stmmac_priv *priv,

-- 
2.53.0