[PATCH net v2] net: ethernet: cortina: Drop half-assembled SKB

[Linus Walleij <linusw@kernel.org>]

From: Andreas Haarmann-Thiemann <eitschman@nebelreich.de>

In gmac_rx() (drivers/net/ethernet/cortina/gemini.c), when
gmac_get_queue_page() returns NULL for the second page of a multi-page
fragment, the driver logs an error and continues — but does not free the
partially assembled skb that was being assembled via napi_build_skb() /
napi_get_frags().

Free the in-progress partially assembled skb via napi_free_frags()
and increase the number of dropped frames appropriately
and assign the skb pointer NULL to make sure it is not lingering
around, matching the pattern already used elsewhere in the driver.

Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Signed-off-by: Andreas Haarmann-Thiemann <eitschman@nebelreich.de>
Signed-off-by: Linus Walleij <linusw@kernel.org>
---
Changes in v2:
- Fix up the commit message so it is clear what the patch is doing.
- Also increase the number of dropped frames as noted by Li Xiasong.
- Link to v1: https://lore.kernel.org/r/20260330-gemini-ethernet-fix-v1-1-18783a45d13a@kernel.org
---
 drivers/net/ethernet/cortina/gemini.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c
index 4824232f4890..065cbbf52686 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c
@@ -1491,6 +1491,11 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
 		gpage = gmac_get_queue_page(geth, port, mapping + PAGE_SIZE);
 		if (!gpage) {
 			dev_err(geth->dev, "could not find mapping\n");
+			if (skb) {
+				napi_free_frags(&port->napi);
+				port->stats.rx_dropped++;
+				skb = NULL;
+			}
 			continue;
 		}
 		page = gpage->page;

---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260330-gemini-ethernet-fix-604c28c53da1

Best regards,
--  
Linus Walleij <linusw@kernel.org>