net: ethernet: lantiq_etop: fix double free in detach

The number of the currently released descriptor is never incremented
which results in the same skb being released multiple times.

Fixes: 504d472 ("MIPS: Lantiq: Add ethernet driver")
Reported-by: Joe Perches <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Aleksander Jan Bajkowski <[email protected]>
Reviewed-by: Andrew Lunn <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: abajk

drivers/net/ethernet/lantiq_etop.c

@@ -217,9 +217,9 @@ ltq_etop_free_channel(struct net_device *dev, struct ltq_etop_chan *ch)
 	if (ch->dma.irq)
 		free_irq(ch->dma.irq, priv);
 	if (IS_RX(ch->idx)) {
-		int desc;
+		struct ltq_dma_channel *dma = &ch->dma;
 
-		for (desc = 0; desc < LTQ_DESC_NUM; desc++)
+		for (dma->desc = 0; dma->desc < LTQ_DESC_NUM; dma->desc++)
 			dev_kfree_skb_any(ch->skb[ch->dma.desc]);
 	}
 }