[PATCH net v3] net: pch_gbe: handle TX skb allocation failure

[Ruoyu Wang]

pch_gbe_alloc_tx_buffers() allocates an skb for each TX descriptor and
then passes the returned pointer to skb_reserve(). If netdev_alloc_skb()
fails, skb_reserve() dereferences NULL.

Make pch_gbe_alloc_tx_buffers() return an error when an skb allocation
fails. On failure, let pch_gbe_alloc_tx_buffers() clean the partially
allocated TX ring before returning the error. While bringing the device
up, release the RX buffer pool through a shared cleanup helper before
unwinding the IRQ setup.

Fixes: 77555ee72282 ("net: Add Gigabit Ethernet driver of Topcliff PCH")
Signed-off-by: Ruoyu Wang <ruoyuw560@xxxxxxxxx>
---
Changes in v3:
- Move the partial TX ring cleanup into pch_gbe_alloc_tx_buffers(), as
  suggested by Simon Horman.

Changes in v2:
- Add the kernel-doc return value description for
  pch_gbe_alloc_tx_buffers().

 .../ethernet/oki-semi/pch_gbe/pch_gbe_main.c  | 38 ++++++++++++++-----
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c b/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c
index e5a6f59..98091fb 100644
--- a/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c
+++ b/drivers/net/ethernet/oki-semi/pch_gbe/pch_gbe_main.c
@@ -1411,13 +1411,25 @@ pch_gbe_alloc_rx_buffers_pool(struct pch_gbe_adapter *adapter,
 	return 0;
 }
 
+static void pch_gbe_free_rx_buffers_pool(struct pch_gbe_adapter *adapter,
+					 struct pch_gbe_rx_ring *rx_ring)
+{
+	dma_free_coherent(&adapter->pdev->dev, rx_ring->rx_buff_pool_size,
+			  rx_ring->rx_buff_pool, rx_ring->rx_buff_pool_logic);
+	rx_ring->rx_buff_pool_logic = 0;
+	rx_ring->rx_buff_pool_size = 0;
+	rx_ring->rx_buff_pool = NULL;
+}
+
 /**
  * pch_gbe_alloc_tx_buffers - Allocate transmit buffers
  * @adapter:   Board private structure
  * @tx_ring:   Tx descriptor ring
+ *
+ * Return: 0 on success, -ENOMEM if a TX skb allocation fails.
  */
-static void pch_gbe_alloc_tx_buffers(struct pch_gbe_adapter *adapter,
-					struct pch_gbe_tx_ring *tx_ring)
+static int pch_gbe_alloc_tx_buffers(struct pch_gbe_adapter *adapter,
+				    struct pch_gbe_tx_ring *tx_ring)
 {
 	struct pch_gbe_buffer *buffer_info;
 	struct sk_buff *skb;
@@ -1431,12 +1443,17 @@ static void pch_gbe_alloc_tx_buffers(struct pch_gbe_adapter *adapter,
 	for (i = 0; i < tx_ring->count; i++) {
 		buffer_info = &tx_ring->buffer_info[i];
 		skb = netdev_alloc_skb(adapter->netdev, bufsz);
+		if (!skb) {
+			pch_gbe_clean_tx_ring(adapter, tx_ring);
+			return -ENOMEM;
+		}
 		skb_reserve(skb, PCH_GBE_DMA_ALIGN);
 		buffer_info->skb = skb;
 		tx_desc = PCH_GBE_TX_DESC(*tx_ring, i);
 		tx_desc->gbec_status = (DSC_INIT16);
 	}
-	return;
+
+	return 0;
 }
 
 /**
@@ -1878,7 +1895,12 @@ int pch_gbe_up(struct pch_gbe_adapter *adapter)
 			   "Error: can't bring device up - alloc rx buffers pool failed\n");
 		goto freeirq;
 	}
-	pch_gbe_alloc_tx_buffers(adapter, tx_ring);
+	err = pch_gbe_alloc_tx_buffers(adapter, tx_ring);
+	if (err) {
+		netdev_err(netdev,
+			   "Error: can't bring device up - alloc tx buffers failed\n");
+		goto freebuf;
+	}
 	pch_gbe_alloc_rx_buffers(adapter, rx_ring, rx_ring->count);
 	adapter->tx_queue_len = netdev->tx_queue_len;
 	pch_gbe_enable_dma_rx(&adapter->hw);
@@ -1892,6 +1914,8 @@ int pch_gbe_up(struct pch_gbe_adapter *adapter)
 
 	return 0;
 
+freebuf:
+	pch_gbe_free_rx_buffers_pool(adapter, rx_ring);
 freeirq:
 	pch_gbe_free_irq(adapter);
 out:
@@ -1927,11 +1951,7 @@ void pch_gbe_down(struct pch_gbe_adapter *adapter)
 	pch_gbe_clean_tx_ring(adapter, adapter->tx_ring);
 	pch_gbe_clean_rx_ring(adapter, adapter->rx_ring);
 
-	dma_free_coherent(&adapter->pdev->dev, rx_ring->rx_buff_pool_size,
-			  rx_ring->rx_buff_pool, rx_ring->rx_buff_pool_logic);
-	rx_ring->rx_buff_pool_logic = 0;
-	rx_ring->rx_buff_pool_size = 0;
-	rx_ring->rx_buff_pool = NULL;
+	pch_gbe_free_rx_buffers_pool(adapter, rx_ring);
 }
 
 /**
-- 
2.51.0