[PATCH net-next 3/4] net: warn if transport header was not set

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

Make sure skb_transport_header() and skb_transport_offset() uses
are not fooled if the transport header has not been set.

This change will likely expose existing bugs in linux networking stacks.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 include/linux/skbuff.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d58669d6cb91aa30edc70d59a0a7e9d4e2298842..a1c73fccccc68641fe46066e6d1195b31483ca4c 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -42,6 +42,7 @@
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 #include <linux/netfilter/nf_conntrack_common.h>
 #endif
+#include <net/net_debug.h>
 
 /* The interface for checksum offload between the stack and networking drivers
  * is as follows...
@@ -2804,6 +2805,7 @@ static inline bool skb_transport_header_was_set(const struct sk_buff *skb)
 
 static inline unsigned char *skb_transport_header(const struct sk_buff *skb)
 {
+	DEBUG_NET_WARN_ON_ONCE(!skb_transport_header_was_set(skb));
 	return skb->head + skb->transport_header;
 }
 
-- 
2.36.0.512.ge40c2bad7a-goog