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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Jason A. Donenfeld" <Jason@zx2c4.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 453/663] wireguard: device: do not generate ICMP for non-IP packets
Date:   Mon,  1 Mar 2021 17:11:41 +0100
Message-Id: <20210301161204.304229512@linuxfoundation.org>
In-Reply-To: <20210301161141.760350206@linuxfoundation.org>
References: <20210301161141.760350206@linuxfoundation.org>
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From: Jason A. Donenfeld <Jason@zx2c4.com>

[ Upstream commit 99fff5264e7ab06f45b0ad60243475be0a8d0559 ]

If skb->protocol doesn't match the actual skb->data header, it's
probably not a good idea to pass it off to icmp{,v6}_ndo_send, which is
expecting to reply to a valid IP packet. So this commit has that early
mismatch case jump to a later error label.

Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/wireguard/device.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireguard/device.c b/drivers/net/wireguard/device.c
index c9f65e96ccb04..c1fd3e04dd3ba 100644
--- a/drivers/net/wireguard/device.c
+++ b/drivers/net/wireguard/device.c
@@ -138,7 +138,7 @@ static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
 		else if (skb->protocol == htons(ETH_P_IPV6))
 			net_dbg_ratelimited("%s: No peer has allowed IPs matching %pI6\n",
 					    dev->name, &ipv6_hdr(skb)->daddr);
-		goto err;
+		goto err_icmp;
 	}
 
 	family = READ_ONCE(peer->endpoint.addr.sa_family);
@@ -201,12 +201,13 @@ static netdev_tx_t wg_xmit(struct sk_buff *skb, struct net_device *dev)
 
 err_peer:
 	wg_peer_put(peer);
-err:
-	++dev->stats.tx_errors;
+err_icmp:
 	if (skb->protocol == htons(ETH_P_IP))
 		icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
 	else if (skb->protocol == htons(ETH_P_IPV6))
 		icmpv6_ndo_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0);
+err:
+	++dev->stats.tx_errors;
 	kfree_skb(skb);
 	return ret;
 }
-- 
2.27.0