[PATCH] net: nixge: fix skb leak and missing bail on DMA mapping error

[kernelcoredev <sonionwhat@gmail.com>]

When dma_mapping_error() fires during RX buffer refill in nixge_recv(),
the skb allocated by netdev_alloc_skb_ip_align() is never freed, and
execution continues writing a corrupt physical address into the hardware
descriptor ring.

Fix by freeing the skb with dev_kfree_skb() and returning early.

Fixes: 492caffa8a1a ("net: ethernet: nixge: Add support for National Instruments XGE netdev")

Signed-off-by: Bentley Blacketer <sonionwhat@gmail.com>
---
 drivers/net/ethernet/ni/nixge.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/ni/nixge.c b/drivers/net/ethernet/ni/nixge.c
index 230d5ff99..b64e2f355 100644
--- a/drivers/net/ethernet/ni/nixge.c
+++ b/drivers/net/ethernet/ni/nixge.c
@@ -645,8 +645,9 @@ static int nixge_recv(struct net_device *ndev, int budget)
 					  NIXGE_MAX_JUMBO_FRAME_SIZE,
 					  DMA_FROM_DEVICE);
 		if (dma_mapping_error(ndev->dev.parent, cur_phys)) {
-			/* FIXME: bail out and clean up */
-			netdev_err(ndev, "Failed to map ...\n");
+			netdev_err(ndev, "Failed to map RX buffer\n");
+			dev_kfree_skb(new_skb);
+			return packets;
 		}
 		nixge_hw_dma_bd_set_phys(cur_p, cur_phys);
 		cur_p->cntrl = NIXGE_MAX_JUMBO_FRAME_SIZE;
-- 
2.54.0