net: macb: drop in-flight Tx SKBs on close

The MACB driver has since forever leaked the outgoing SKBs that
have not yet been marked as completed. They live in queue->tx_skb
which gets freed without remorse nor checking.

macb_free_consistent() gets called in a few codepaths, but only close will
trigger the added expressions. In macb_open() and macb_alloc_consistent()
failure cases, queues' tx_skb just got allocated and are empty.

Fixes: 89e5785fc8a6 ("[PATCH] Atmel MACB ethernet driver")
Cc: stable@vger.kernel.org
Reviewed-by: Nicolai Buchwitz <nb@tipi-net.de>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://patch.msgid.link/20260702-macb-drop-tx-v4-1-1c833eebdbc8@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index fd282a1700fb98413a0d315a86a8e9d7caed76f4..d394f1f43b685eee64f99eae2f2ac5b2949c1274 100644 (file)
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2668,8 +2668,25 @@ static void macb_free_consistent(struct macb *bp)
        dma_free_coherent(dev, size, bp->queues[0].rx_ring, bp->queues[0].rx_ring_dma);
 
        for (q = 0, queue = bp->queues; q < bp->num_queues; ++q, ++queue) {
-               kfree(queue->tx_skb);
-               queue->tx_skb = NULL;
+               if (queue->tx_skb) {
+                       unsigned int dropped = 0, tail;
+
+                       for (tail = queue->tx_tail; tail != queue->tx_head;
+                            tail++) {
+                               if (macb_tx_skb(queue, tail)->skb)
+                                       dropped++;
+                               macb_tx_unmap(bp, macb_tx_skb(queue, tail), 0);
+                       }
+
+                       queue->stats.tx_dropped += dropped;
+                       bp->dev->stats.tx_dropped += dropped;
+
+                       kfree(queue->tx_skb);
+                       queue->tx_skb = NULL;
+               }
+
+               queue->tx_head = 0;
+               queue->tx_tail = 0;
                queue->tx_ring = NULL;
                queue->rx_ring = NULL;
        }