net: ethernet: mtk_wed: fix possible NULL pointer dereference in mtk_wed_wo_queue_tx_...

In order to avoid a NULL pointer dereference, check entry->buf pointer before running
skb_free_frag in mtk_wed_wo_queue_tx_clean routine.

Fixes: 799684448e3e ("net: ethernet: mtk_wed: introduce wed wo support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/3c1262464d215faa8acebfc08869798c81c96f4a.1702827359.git.lorenzo@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/mediatek/mtk_wed_wo.c b/drivers/net/ethernet/mediatek/mtk_wed_wo.c
index 3bd51a3d6650010464bc7645eb20e45fa70f5ae3..ae44ad5f8ce8a1e9894f6a2175f0c92642979389 100644 (file)
--- a/drivers/net/ethernet/mediatek/mtk_wed_wo.c
+++ b/drivers/net/ethernet/mediatek/mtk_wed_wo.c
@@ -291,6 +291,9 @@ mtk_wed_wo_queue_tx_clean(struct mtk_wed_wo *wo, struct mtk_wed_wo_queue *q)
        for (i = 0; i < q->n_desc; i++) {
                struct mtk_wed_wo_queue_entry *entry = &q->entry[i];
 
+               if (!entry->buf)
+                       continue;
+
                dma_unmap_single(wo->hw->dev, entry->addr, entry->len,
                                 DMA_TO_DEVICE);
                skb_free_frag(entry->buf);