net: geneve: check skb is large enough for IPv4/IPv6 header

Check within geneve_xmit_skb/geneve6_xmit_skb that sk_buff structure is large enough to include IPv4 or IPv6 header, and reject if not. The geneve_xmit_skb portion and overall idea was contributed by Eric Dumazet. Fixes a KMSAN-found uninit-value bug reported by syzbot at: https://syzkaller.appspot.com/bug?id=abe95dc3e3e9667fc23b8d81f29ecad95c6f106f Suggested-by: Eric Dumazet <[email protected]> Reported-by: [email protected] Signed-off-by: Phillip Potter <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
zandrey · Apr 11, 2021 · 6628ddf · 6628ddf
1 parent 31457db
commit 6628ddf
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
@@ -891,6 +891,9 @@ 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)))
+		return -EINVAL;
+
 	sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
 	rt = geneve_get_v4_rt(skb, dev, gs4, &fl4, info,
 			      geneve->cfg.info.key.tp_dst, sport);
@@ -985,6 +988,9 @@ 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)))
+		return -EINVAL;
+
 	sport = udp_flow_src_port(geneve->net, skb, 1, USHRT_MAX, true);
 	dst = geneve_get_v6_dst(skb, dev, gs6, &fl6, info,
 				geneve->cfg.info.key.tp_dst, sport);