Commit f9aefd6b authored by Eric Dumazet's avatar Eric Dumazet Committed by Paolo Abeni
Browse files

net: warn if mac header was not set 



Make sure skb_mac_header(), skb_mac_offset() and skb_mac_header_len() uses
are not fooled if the mac header has not been set.

These checks are enabled if CONFIG_DEBUG_NET=y

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

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220620093017.3366713-1-eric.dumazet@gmail.com


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 4336487e

include/linux/skbuff.h

+7 −5
Original line number Diff line number Diff line
@@ -2763,8 +2763,14 @@ static inline void skb_set_network_header(struct sk_buff *skb, const int offset) 
	skb->network_header += offset;

}



static inline int skb_mac_header_was_set(const struct sk_buff *skb)

{

	return skb->mac_header != (typeof(skb->mac_header))~0U;

}



static inline unsigned char *skb_mac_header(const struct sk_buff *skb)

{

	DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));

	return skb->head + skb->mac_header;

}
@@ -2775,14 +2781,10 @@ static inline int skb_mac_offset(const struct sk_buff *skb) 


static inline u32 skb_mac_header_len(const struct sk_buff *skb)

{

	DEBUG_NET_WARN_ON_ONCE(!skb_mac_header_was_set(skb));

	return skb->network_header - skb->mac_header;

}



static inline int skb_mac_header_was_set(const struct sk_buff *skb)

{

	return skb->mac_header != (typeof(skb->mac_header))~0U;

}



static inline void skb_unset_mac_header(struct sk_buff *skb)

{

	skb->mac_header = (typeof(skb->mac_header))~0U;