netdev - [PATCH v2] net: geneve: modify IP header check in geneve6_xmit_skb and geneve_xmit

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Message-Id: <20210422234945.1190-1-phil@philpotter.co.uk>
Date:   Fri, 23 Apr 2021 00:49:45 +0100
From:   Phillip Potter <phil@...lpotter.co.uk>
To:     davem@...emloft.net
Cc:     kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, sd@...asysnail.net,
        edumazet@...gle.com, fw@...len.de
Subject: [PATCH v2] net: geneve: modify IP header check in geneve6_xmit_skb and geneve_xmit_skb

Modify the header size check in geneve6_xmit_skb and geneve_xmit_skb
to use pskb_inet_may_pull rather than pskb_network_may_pull. This fixes
two kernel selftest failures introduced by the commit introducing the
checks:
IPv4 over geneve6: PMTU exceptions
IPv4 over geneve6: PMTU exceptions - nexthop objects

It does this by correctly accounting for the fact that IPv4 packets may
transit over geneve IPv6 tunnels (and vice versa), and still fixes the
uninit-value bug fixed by the original commit.

Reported-by: kernel test robot <oliver.sang@...el.com>
Fixes: 6628ddfec758 ("net: geneve: check skb is large enough for IPv4/IPv6 header")
Suggested-by: Sabrina Dubroca <sd@...asysnail.net>
Signed-off-by: Phillip Potter <phil@...lpotter.co.uk>
---

V2:
* Incorporated feedback from Sabrina Dubroca regarding pskb_inet_may_pull
* Added Fixes: tag as requested by Eric Dumazet

---
 drivers/net/geneve.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index 42f31c681846..61cd3dd4deab 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -891,7 +891,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	__be16 sport;
 	int err;
 
-	if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
+	if (!pskb_inet_may_pull(skb))
 		return -EINVAL;
 
 	sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
@@ -988,7 +988,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	__be16 sport;
 	int err;
 
-	if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
+	if (!pskb_inet_may_pull(skb))
 		return -EINVAL;
 
 	sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
-- 
2.30.2