openwrt/target/linux/lantiq/patches-5.10/0717-v6.0-net-lantiq_xrx200-confirm-skb-is-allocated-before-us.patch

From c8b043702dc0894c07721c5b019096cebc8c798f Mon Sep 17 00:00:00 2001
From: Aleksander Jan Bajkowski <olek2@wp.pl>
Date: Wed, 24 Aug 2022 23:54:06 +0200
Subject: [PATCH] net: lantiq_xrx200: confirm skb is allocated before using

xrx200_hw_receive() assumes build_skb() always works and goes straight
to skb_reserve(). However, build_skb() can fail under memory pressure.

Add a check in case build_skb() failed to allocate and return NULL.

Fixes: e015593573b3 ("net: lantiq_xrx200: convert to build_skb")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Aleksander Jan Bajkowski <olek2@wp.pl>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 drivers/net/ethernet/lantiq_xrx200.c | 6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -239,6 +239,12 @@ static int xrx200_hw_receive(struct xrx2
 	}
 
 	skb = build_skb(buf, priv->rx_skb_size);
+	if (!skb) {
+		skb_free_frag(buf);
+		net_dev->stats.rx_dropped++;
+		return -ENOMEM;
+	}
+
 	skb_reserve(skb, NET_SKB_PAD);
 	skb_put(skb, len);